it was at five o'clock______he went home

问题描述:

it was at five o'clock______he went home
A.when B.that C.since D.before
为什么选B,不选A
it was in the office _______ he works
A.that B.which C.as D.where
为什么选D,不选A

it is/was …that 是强调句 ,如果选A,则去掉at