---Listen! Who in the next room?-I think Sam is.A. singB. singsC. singingD. is singing

发布时间：2020-08-21 05:08:35

---Listen! Who      in the next room?
---I think Sam is.
A. sing
B. sings
C. singing
D. is singing

网友回答

A. sing
B. sings
C. singing
(答案→)D. is singing
解析：根据listen 可判断时态为现在进行时，故选D
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