ことは～がI did, but…; it is, but…
You say the same word twice around ことは to grant the bare fact, no more: "I did watch it", "it is big". Then が or けど brings the catch, and that half is the point.
I did watch the movie, but I fell asleep several times during it.
This room is big, I'll admit, but the rent is far too high.
Verb
読むことは読む + が／けど
The second one carries the tense and the politeness: 読むことは読んだ, 読むことは読みました. For the past the first can be past too: 読んだことは読んだ.
い-adjective
高いことは高い + が／けど
な-adjective
静かなことは静かだ + が／けど
Noun
休みは休みだ + が／けど
A noun usually goes without こと: the noun, は, the noun again.
- After it
- が, けど or けれども, then what was missing or wrong.
- Tone
- Lukewarm. You give the smallest yes that is still true.
- Where you'll meet it
- Conversation, with けど: answers to "did you…?" and "how was it?" when a plain yes would say too much. With が, in writing too.
In use
How was the new ramen place by the station?
It's good, I'll give it that, but it's a bit pricey.
I'll go to that shop, sure, but I don't think I'll buy anything.
I did read the materials, but I wasn't able to check the detailed figures.
This library is quiet, true, but it doesn't have many seats.
Today is a day off, technically, but I plan to work at home.
The second half is the point
I read the book, but I didn't really understand it.
Two facts, side by side.
I did read the book, but I didn't really understand it.
You admit the reading and play it down. What follows is what you want heard.
The repeat is not "really" or "very". おいしいことはおいしい is faint praise, and whoever hears it waits for the けど.
Close neighbours
A weak yes made of two negatives: possible, or true up to a point. ことは～が gives the bare fact a full yes.
I can eat it, I suppose, but it's not a taste I like much.
わけではないN3
"It's not that…": you take back a conclusion the other person might jump to. Often it means "not entirely".
I chose the online course, but that does not mean I dislike learning in a classroom.
Check yourself
1What is B saying?
A
Choose an answer to see why.
2"I did go to the party, but I left after thirty minutes."
パーティーには
Choose an answer to see why.
More detail
には can stand in for ことは with the same meaning.
I do have an umbrella, but it's broken.
More sentences
I did meet the company president, but we only exchanged greetings.
The food was good, yes, but I didn't think it was worth the price.
The procedure was simple enough, but it took a week to complete.