一、when, while和as1When既可引导一个持续动作，也可引导一个短暂动作，可用于主句和从句动作同时发生或从句动作先于主句动作。当主句是将来时，从句的时态用现在时。（when在实际中用得最多）I told my children when Lincoln was your age he walked twelve miles to school everyday. But my son said, “Thats nothing. When he was your age, he was president.”我告诉我的孩子：当林肯你那么大岁数时他每天走12英里去学校，我儿子说，“那没什么，当他你那么大岁数时已经当总统了”。Theres a side to President Reagan that people dont know. When he was a young man, he read complete works of Shakespeare. Of course, when Reagan was young, Shakespeare h
