かと思うと・
One thing has only just happened when another follows, often the opposite. You are an onlooker telling what you saw.
One moment my little brother was crying, and the next he is laughing.
No sooner had the baby fallen asleep than it woke up again.
How to form it
Verb in the た-form + かと思うと／かと思ったら
眠った → 眠ったかと思うと. かと思ったら is the one people say; かと思うと is more written. 思う is not "I thought" here: the first thing did happen.
- Before it
- Something that has only just happened: 泣いた, 眠った, やんだ, 出ていった.
- After it
- What came next, often the opposite: もう笑っている, また止まった.
- Said about
- Other people and things: a child, a cat, the weather, a train. Not what you did yourself.
- Where you'll meet it
- Stories and descriptions; in conversation, for how changeable someone or the weather is.
In use
No sooner had the rain stopped than it began to hail.
The train had only just started moving when it stopped again.
No sooner had he left the room than he came back for something he had forgotten.
Not what you did yourself
English can say "no sooner had I got home than I went out again". かと思うと can't: it tells what you watched happen.
No sooner had my brother come home than he went out again.
Not said: 私は
(No sooner had I come home than I went out again.)
About yourself it is the て-form: 家に帰って、すぐまた出かけた.
Close neighbours
たとたん（に）N3
The everyday one. The very moment one thing was done, something else happened, suddenly and not by your choice.
The moment I sat down, the phone rang.
The verb twice, plain and then negative: "had barely … when". The second thing begins almost on top of the first.
He had barely sat down when he stood up again.
矢先にN2
"Just as I was about to", or when something had only just happened: something else cuts across it. Mostly bad timing.
Just as we were about to leave on a family trip, our son came down with a fever.
かと思ったN3
The same words as a real thought that turned out wrong: "I thought it was …, but". What follows shows which it is.
I thought it was rain, but it was snow.
Check yourself
1Which sentence sounds natural?
Choose an answer to see why.
2What does this say?
うちの
Choose an answer to see why.
More detail
The か can drop (出たと思ったら), and there is a third shape, かと思えば:
In the mountains, no sooner does it clear up than it rains.
かと思えば also sets two unlike things side by side, with no timing in it:
Some students come every day, and then there are others who never come at all.
More sentences
No sooner had the wind died down than it suddenly began to blow hard.
The cat had only just come up close when it darted away onto the wall.