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
网友回答
A. the door bell rang
B. the door bell rings
C. 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。