——I have heard that they will go to Beijing.Do you know when they____?

问题描述:

——I have heard that they will go to Beijing.Do you know when they____?
——Sorry,I don't know.
A.will leave
B.leave
C.left
D.would leave

B,因为像这种表示计划好的事情,可以用一般现在时表达将来的意思,这是将来时的特殊表达形式