The old lady was standing by the window ____ suddenly she caught sight of a postman riding along.A.whenB.whileC.becauseD.so

问题描述:

The old lady was standing by the window ____ suddenly she caught sight of a postman riding along.
A.when
B.while
C.because
D.so

A

A
When:当……时
while:当……时,一般双方都是进行时,强调一种对比
because:因为
so:所以