非谓语中doing 和 having done的区别

题目

非谓语中doing 和 having done的区别
比如____in thought,he almost ran into the car in front of him
这里填LOST 而不是 having lost
而 ______his letter,i will write another letter to him
这里就要填having not received~

答案

明显发生在主句前的用having done,无明显先后顺序的,不用完成时.