问题:
While the boy ______ down the street, the UFO _____ .
A.was walking; was landing
B.walked; landed
C.was walking; landed
D.walked; was landing
While the boy ______ down the street, the UFO _____ .
A.was walking; was landing
B.walked; landed
C.was walking; landed
D.walked; was landing
A.was walking; was landing
B.walked; landed
C.was walking; landed
D.walked; was landing
参考答案: