12 — Master mixed review

What this fixes for you: this is the capstone. One big practice set that mixes every topic so far — articles, much/many, agreement, tenses, possessives, prepositions, punctuation, run-ons, confused words, and spelling — so the rules stick instead of fading after each separate lesson.

This doc is mostly drills. There’s a short warm-up, then 28 mixed exercises (including a few “clean up this messy dev message” tasks), then a full answer key with one-line explanations. Work through it with a pen or in a scratch file, then check yourself.

How to use this

• Don’t peek at the answer key until you’ve tried the whole set.
• Write your fix out in full — don’t just think “yeah, I know that one.” The point is to train your fingers, because you write commits and Slack messages on autopilot.
• After checking, note which topics you missed most. Re-read that lesson (see 00-index.md).

A quick reminder of what’s being tested

Topic	The one thing to remember
Articles	Don’t drop a / an / the: “open a pull request”, not “open pull request”.
Much / many	many + countable plural (“many bugs”); much + uncountable (“much progress”).
Agreement	Singular subject → singular verb: “the test passes”, “the tests pass”.
Tenses	”I fixed it” (done), “I have fixed it” (done, still relevant), “I’m fixing it” (now).
Possessives	its = belonging to it; it’s = it is. your vs you’re.
Prepositions	”merge into main”, “depends on the API”, “blocked by the migration”.
Punctuation	End sentences with a full stop. Use commas to break up clauses.
Capitalization	Always capital I. Capitalize the first word of every sentence.
Run-ons	Two complete thoughts need a full stop, a semicolon, or a comma + and/but.
Confused words	their/there/they’re, then/than, affect/effect, lose/loose.
Spelling	grammar, research, separate, receive, occurred, definitely.
Texting leak	No “u”, “ur”, “thx” in professional writing. Write it out.

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Drills

Part A — Fix the sentence

Each line has one or more errors. Rewrite it correctly.

1. i pushed the fix to ur branch can u review it

2. we are making so much mistake in the checkout flow

3. the migration are still running, it has not finished yet

4. please open pull request against main branch

5. i did a lot of reaseach on grammer before writing this doc

6. the API return 500 when the cart is empty we should add a guard

7. your right, the cache key was wrong its fixed now

8. there is to many open tickets in the backlog this sprint

9. the deploy effected all tenants because the config was shared

10. i think this approach is more better then the old one

Part B — Fill the blank

Choose the right word and write the full sentence.

11. The pricing service depends ______ the tenant context being initialized first. (on / from / to)

12. We merged the hotfix ______ main and tagged a release. (into / in / to)

13. There ______ three failing tests in the payment suite right now. (is / are)

14. ______ the queue worker still running, or did it crash? (Is / Are)

15. I’ve reviewed the PR; ______ ready to merge once CI passes. (its / it’s)

16. Please update ______ local .env before running the seeder. (your / you’re)

17. We didn’t have ______ time to write tests for the edge cases. (much / many)

18. There were ______ duplicate rows after the bad import. (much / many)

19. The bug only appears ______ the user has more than one address. (then / when)

20. This fix is faster ______ the previous one by about 40 ms. (then / than)

Part C — Choose A or B

21. (A) “The endpoint returns it’s payload as JSON.” (B) “The endpoint returns its payload as JSON.”

22. (A) “Each tenant have their own subdomain.” (B) “Each tenant has its own subdomain.”

23. (A) “I have already deployed it yesterday.” (B) “I deployed it yesterday.”

24. (A) “We need to separate the read and write paths.” (B) “We need to seperate the read and write paths.”

Part D — Clean up the messy dev message

Rewrite each so a teammate could read it without effort. Fix spelling, capitals, full stops, run-ons, articles, much/many, and the texting style.

25. A run-on Slack standup: yesterday i worked on the cart bug today i am doing the checkout flow i found so much issue in the validation also the API is slow we should look at it tmrw can u help

26. A sloppy commit message: fixed stuff in pricing also some other thing, broke the test but its fine i think will fix latter

27. A confusing PR description: this PR change the order service so it dont crash when address is missing i also did some refactor and remove dead code there is still much bug but this is good for now plz review

28. The learner’s own line (the one that started this course): can u do reaseach on grammer for me and teach me i already know but as of now i am making so much mistake

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Answer key

Part A

1. “I pushed the fix to your branch. Can you review it?” — Capital I, “your” not “ur”, “you” not “u”, split into two sentences, and it’s a question so it ends with ?.

2. “We are making so many mistakes in the checkout flow.” — “mistake” is countable, so many + plural mistakes. This is your signature slip.

3. “The migration is still running; it hasn’t finished yet.” — “migration” is singular → is. Two thoughts joined; use a semicolon (or a full stop) instead of a comma. (A comma alone between two complete sentences is a comma splice.)

4. “Please open a pull request against the main branch.” — Add a before “pull request” and the before “main branch”. You routinely drop these articles.

5. “I did a lot of research on grammar before writing this doc.” — Capital I, “research” (not “reaseach”), “grammar” (not “grammer”). Memorize both spellings — they show up constantly in your work.

6. “The API returns a 500 when the cart is empty. We should add a guard.” — “The API” is singular → returns; add a before “500”; split the run-on into two sentences.

7. “You’re right. The cache key was wrong; it’s fixed now.” — “You’re” = “you are”; “it’s” = “it is” (here it means “it is fixed”). New sentence after “right”.

8. “There are too many open tickets in the backlog this sprint.” — “tickets” is plural → are; too (excessive), not “to”; many with countable tickets.

9. “The deploy affected all tenants because the config was shared.” — affected (verb) not “effected”; “effect” is usually the noun. Memorize: affect = action, effect = result.

10. “I think this approach is better than the old one.” — Capital I; “more better” is doubled — just better; than for comparison, not “then”.

Part B

11. on — “depends on something.” Fixed preposition.

12. into — you merge changes into a branch (movement toward a target).

13. are — “three failing tests” is plural.

14. Is — “the queue worker” is singular; also capital at the start of the sentence.

15. it’s — “it’s ready” = “it is ready.”

16. your — possessive: the .env belonging to you. (“you’re” = “you are”.)

17. much — “time” is uncountable.

18. many — “rows” is countable plural.

19. when — the bug appears when a condition is met. (“then” = next/after.)

20. than — comparison uses than.

Part C

21. B — “its payload” (belonging to it). “it’s” would mean “it is payload,” which is nonsense.

22. B — “Each tenant” is singular → has + its. (“Each” is always singular, even though it feels like many.)

23. B — “yesterday” is a finished time, so use simple past deployed, not present perfect “have deployed.” Don’t mix “already…yesterday.”

24. A — separate is the correct spelling. Mnemonic: there’s a rat in separate.

Part D

25. Run-on Slack standup — cleaned up:

Yesterday I worked on the cart bug. Today I’m on the checkout flow. I found many issues in the validation. The API is also slow — we should look at it tomorrow. Can you help?

What changed: capital I throughout; full stops between each thought (no more run-on); many issues (countable) not “so much issue”; “tomorrow” not “tmrw”; “you” not “u”; the question gets a ?.

26. Sloppy commit message — cleaned up:

Fix pricing rounding bug; also adjust the tier lookup. One test is failing — will fix in a follow-up.

What changed: capital first word; full stops; its → it’s isn’t even needed once you say it plainly; “latter” → later (latter = the second of two things, later = afterward); say what you fixed instead of “stuff” and “some other thing” so the log is searchable. A commit subject is best in the imperative (“Fix…”, “Add…”), short, and specific.

27. Confusing PR description — cleaned up:

This PR changes the order service so it doesn’t crash when the address is missing. I also refactored and removed some dead code. There are still a few known bugs, but this is a good checkpoint. Please review.

What changed: “change → changes” (the PR is singular); “dont → doesn’t”; add the before “address”; There are still a few bugs (countable → “a few”, not “much”); split the run-on; Please and “review” spelled out (no “plz”); capital I.

28. Your original line — corrected:

Can you do research on grammar for me and teach me? I already know it, but right now I’m making so many mistakes.

What changed: “u → you”; “reaseach → research”; “grammer → grammar”; it’s a request, so it ends with ?; capital I; “i already know” needs an object → “I already know it”; “as of now” → right now; so many mistakes (countable plural) instead of “so much mistake.” That last one is the single most common mistake in your writing — when you can count it, use many and add the -s.

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You’ve now touched every rule in the course in one sitting. The three habits that will buy you the most respect in commits, PRs, and standups: (1) end every sentence with a full stop, (2) capital I always, and (3) count it before you write much vs many. Keep this file bookmarked and redo it in a week — if you score the same drills clean twice, the rules have stuck.

Part of the Developer English course — see 00-index.md.