非谓语动词改成从句后动词形式会怎么变化?

问题描述:

非谓语动词改成从句后动词形式会怎么变化?
保持不变吗?

非谓语动词改为从句后,必须由原来的非谓语形式改为谓语形式,即必须在从句中作谓语.
eg Not knowing what to do,they had to wait for the teacher.(非谓语动词作原因状语)
Because the didn't know what to do,they had to wait for the teacher.(从句)
Asked by the police,the man was very nervous.(非谓语动词作时间状语)
When he was asked by the police,the man was very nervous(从句)
供参考.