The old lady was standing by the window ____ suddenly she caught _英语解答

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

人气：108 ℃　时间：2020-05-14 04:00:33

解答

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