It was on the National Day （ ） she met with her separated sister.
（A）that
（B）where
（C）when
（D）which
Was it last summer （ ） you and your friends went to Moscow?
（A）when
（B）how
（C）which
（D）that
It's a long time ago （ ） I saw you last time.
（A）when
（B）since
（C）for
（D）that
