问题描述:
One day while I ____ along the street,I ____ someone calling.
A.walked…was hearing B.was walking…has heard
C.was walking…had heard D.was walking…heard
为什么选D不选C
A.walked…was hearing B.was walking…has heard
C.was walking…had heard D.was walking…heard
为什么选D不选C
问题解答:
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