Today’s Question

とき can be replaced with
a. あと b. こと c. さい d. まえ

Today’s Grammar Point: ~さい

さい is a very formal alternative for ~とき, which can be translated as “when ~” or “at the time when ~.” As さい is a very formal expression, it is often used within an honorific expression. Most さい can be replaced with とき but there are some occasions you can’t. See the examples below.


  • この/その/あの + さい
  • [noun] のさい
  • [plain form verb] さい


Let’s stop it on this occasion.
このさい is a set expression meaning “now,” “in these cercumstances,” etc, and you cannot swap it with このとき.

Thank you for your help at that occasion.
そのときは is not wrong but as it is very informal, it does not match the formal feel of お世話せわになりました.

Fasten your seat belt when taking off.
My impression is that さい covers a slightly longer period than とき, so I get the feeling that 離陸りりくさい includes the period when the aeroplane is moving on the ground while 離陸りりくのとき sounds more like the very short period when the aeroplane gets airborne.

Please drop in when you come nearby.

前回ぜんかい旅行りょこうさい写真しゃしんです。(formal) – Today’s Question Sentence
This is a photo during my last trip.

Please switch off your mobile phone when boarding.

When I get in the car, I always fasten my seat belt.

I will definitely come to you when I go back to Japan next time.

When I went to Holland, I went to the Van Gogh Museum.

Here is the receipt I got when I bought this carpet.

Answer to Today’s Question: c

See above

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