Question

ゲスト

①He called his mother immediately because he saw a stranger approaching his house.
②He had no sooner seen a stranger approaching his house than called his mother.
③He had hardly seen a stranger approaching his house when called his mother.
④He had scarcely seen a stranger approaching his house before called his mother.

この4つの英文は同じですか？

Answer 1

黒龍

2,3,4は｢～するとすぐに｣という構文ですね、同じです。
ただ、1は少し違いますね。2,3,4はwhen,beforeなどで文が時系列で繋がっています。
対して、1はbecauseを繋いでいるので、原因と結果の関係です。

ニュアンスはさほど変わりませんが、文法上はこのような違いがあります。