While dancing happily at home, A. the door bell rangB. the door bell ringsC. we heard the

While dancing happily at home, ．
A. the door bell rang
B. the door bell rings
C. we heard the door bell rings
D. we heard the door bell ring

A. the door bell rangB. the door bell ringsC. we heard the door bell rings(答案→)D. we heard the door bell ring解析：由句子结构上看，前后的动作执行者应该一致，所以排除A和B。C想是个宾语从句，要注意时态一致，如果将rings改成rang才可以。

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