That cool (That is cool)

People often drop the linking verb after the demonstrative that and end up with clipped fragments like "That very cool." In standard English a subject needs a verb: add is/was or use the contraction that's to complete the thought.

Below are quick rules, concentrated wrong→right pairs, rewrites for work/school/casual contexts, and a three-step checklist you can use right away.

Quick answer

When that begins a clause followed by an adjective or noun phrase, include a copula (is/was) or use the contraction that's. Change "That very cool" → "That is very cool" or "That's very cool." Use the full form in formal writing and that's in informal contexts.

If present: use "That is" or "That's". If past: use "That was".
Prefer the full copula in formal writing; contractions are fine in speech and informal messages.
If the complement is a noun phrase, add an article or possessive when needed: "That's a problem" or "That's his idea."

Core explanation: what's missing and why

That as a demonstrative can head a clause, but clauses require a verb to link subject and complement. The missing word is the copula (is/was).

Fixes: insert the copula (That is...), use the contraction (That's...) for informal speech, or rephrase the sentence so that that is followed by a verb.

Typical pattern: That + adjective/noun → needs is/was or that's.
Omitting the copula creates a sentence fragment in standard written English.
Wrong → Right:
Wrong: That very cool. →
Right: That is very cool. / That's very cool.
Wrong → Right:
Wrong: That amazing. →
Right: That is amazing. / That's amazing.

Grammar essentials: copula, contractions, and time

The copula (is/are/was/were) links a subject to a predicate. Contractions like that's contain the copula and suit informal tone; the full form suits formal prose.

Present/general statements: use "is" or "that's". Past events: use "was".
When the complement is a noun, include articles: "That's a mess," not "That's mess."
Wrong → Right:
Wrong: That pretty wild last night. →
Right: That was pretty wild last night.
Wrong → Right:
Wrong: That everyone's fault. →
Right: That's everyone's fault.

Real usage: pick the right register (work, school, casual)

Match form to audience. Full copula for formal writing, contractions for casual speech or chat.

Work (formal report): That is a critical risk to the timeline.
Work (team chat): That's a useful summary - thanks.
Work (email to client): That is an issue we will resolve by Friday.
School (essay): That is the most compelling counterargument.
School (discussion post): That's the theorem we used in class.
School (feedback): That conclusion requires more supporting data.
Casual (text): That's so cool!
Casual (spoken): That was hilarious last night.
Casual (social post): That's my favorite song right now.

Examples and common corrections (many wrong → right pairs)

Copy any of the Right forms into your writing. Each wrong example shows the typical omission or small error.

Wrong: That very cool. →
Right: That is very cool. / That's very cool.
Wrong: That amazing photo you took. →
Right: That's an amazing photo you took.
Wrong: That not what I meant. →
Right: That's not what I meant.
Wrong: That deadline tight. →
Right: That deadline is tight.
Wrong: That answer incorrect. →
Right: That answer is incorrect.
Wrong: That guy hilarious. →
Right: That guy is hilarious.
Wrong: That so cool. →
Right: That's so cool.
Wrong: That everyone's problem. →
Right: That's everyone's problem.
Wrong: That ridiculous. →
Right: That is ridiculous. / That's ridiculous.
Rewrite: "That very cool" → "That's very cool." (casual) or "That is very cool." (formal)
Rewrite: "That amazing discovery" → "That's an amazing discovery." or more
formal: "That discovery is remarkable."
Rewrite: "That that was unexpected" → "That was unexpected."

Rewrite help: three quick steps to fix any sentence

When you see a fragment starting with that, follow these steps to fix it quickly.

Step 1: Read it aloud and insert "is" - if it now sounds like a sentence, add "is" or "that's".
Step 2: Check time - use "was" if you mean the past.
Step 3: If the complement is a noun, add the required article or possessive ("a", "the", "my").

Original: "That very cool" →
Fixed: "That's very cool."
Original: "That amazing photo you took." →
Fixed: "That's an amazing photo you took."
Original: "That not the answer" →
Fixed: "That's not the answer." / "That is not the answer."
Alternative rewrite: change the subject - "I found that surprising." instead of "That surprising."

Try your own sentence

Test the whole sentence rather than the phrase by itself; context usually makes the right choice clear.

Memory tricks and a short checklist

Use these quick tests before you send a message or submit writing.

"Is/Was test": Insert "is" or "was" after that and read it. If it sounds like a sentence, you needed the copula.
"Complete thought test": Ask whether the fragment answers how/why. If not, add the copula.
Quick checklist: 1) Is there a verb? 2) Present or past? 3) Does the complement need an article?
Usage example: See "That funny" → try "That is funny." (Is/Was test passed.)

Hyphenation, punctuation, and small formatting pitfalls

Dropping the copula often accompanies other small errors: missing hyphens in compound modifiers, missing articles, and punctuation slips. Fix the copula first, then check these items.

Compound modifiers before a noun need hyphens: "That is a well-known issue."
Commas don't replace verbs - add "is" if a new clause requires one after a comma.
Confirm article presence after fixing the copula: "That's a problem," not "That's problem."
Wrong → Right:
Wrong: That long term problem persists. →
Right: That long-term problem persists. / That is a long-term problem.
Usage: "We investigated it, and that was surprising." - correct: verb after comma.

Spacing, contractions, and apostrophe mistakes

When you change "That very cool" to "That's very cool", watch for missing apostrophes and spacing errors that create new mistakes.

Write the contraction with an apostrophe: that's. Missing apostrophe gives "thats", which is incorrect.
Keep a space after punctuation and between words when you paste rewrites into chat or captions.
Wrong → Right:
Wrong: Thats very cool. →
Right: That's very cool.
Wrong → Right:
Wrong: That'svery cool. →
Right: That's very cool.

Similar mistakes to watch for

Fixing the copula is one step - also check for dropped auxiliaries, wrong demonstratives, and missing articles.

Dropped auxiliary: "I been there" → "I have been there" or "I've been there."
Demonstrative choice: "This is" (near) vs. "That is" (far) - pick based on context.
Missing article after contraction: "That's good idea" → "That's a good idea."
Wrong → Right:
Wrong: I been busy. →
Right: I have been busy. / I've been busy.
Dialect note: Some dialects use zero copula; be aware of your audience and use standard forms in formal writing.

FAQ

Is it okay to say "That very cool" in conversation?

You may hear it in very casual speech, but it's nonstandard. For clarity and correctness in writing and formal speech use "That is very cool" or "That's very cool."

When should I use "that is" vs "that's" vs "that was"?

"That is" or "that's" for present or general statements; "that was" for past events. Prefer the full form in formal writing; contractions are fine in informal contexts.

Why does "That very cool" sound incomplete?

Because it lacks the copula that links the subject to its complement. Without a verb the clause is a fragment in standard English.

How do I fix sentences like "That amazing work" in an essay?

Add the copula and, if helpful, an article: "That is amazing work." Or for emphasis: "That is an amazing piece of work." Use the full form in academic writing.

Will grammar checkers catch dropped copulas?

Many grammar tools flag sentence fragments and suggest adding a verb. They often recommend formal vs. informal alternatives. Still, review suggested fixes for intended meaning (is vs. was, and whether an article is needed).

Want a quick second opinion?

If you're unsure whether to use "that is" or "that's", paste the sentence into a checker or run the three-step checklist above before you hit send to catch most dropped-copula errors instantly.