she heard planes passing overhead and wondered how she could send a signal.
问题描述：
she heard planes passing overhead and wondered how she could send a signal.
请问pass为什么加ing ,wonder为什么加ed,
答
第一个是hear sb/sth doing sth听到……正在做某事（用原形do的话表示全过程）
第二个加ed是因为wondered跟heard并列的,过去式,听到飞机飞过头顶,想知道……