时态\语态 主动 被动
一般式 to do to be done
进行式 to be doing
完成式 to have done to have been done
完成进行式 to have been doing
He seems to know this.
I hope to see you again. = I hope that I'll see you again. 我希望再见到你。
I'm sorry to have given you so much trouble.
He seems to have caught a cold.
He seems to be eating something.
She is known to have been wreaking on the problem for many years.