While watching television .A. the doorbell rang B. the doorbell ringsC. we heard the door

问题补充：

While watching television, .

A. the doorbell rang

B. the doorbell rings

C. we heard the doorbell ring

D. we heard the doorbell rings

答案：

A. the doorbell rang

B. the doorbell rings

(答案→)C. we heard the doorbell ring

D. we heard the doorbell rings

解析：

非谓语动词作状语的用法。根据前半句的While watching television推断主语必须是“观看电视”这动作的发出者，即we；同时主句有have sb. do sth.的句型，省略了to的不不定式做宾补。