是表示征求意见,be to do1)表示安排或计划好了的即将发生的动作。例如:The highway is to be opened in May.2)用来表示征求意见,多用于第一人称疑问句中。例如:Are we to hand in the composition after class?3)表示命令、警告、劝告等。例如:You are to give up smoking.(命令式劝告)You are to be punished if you do that again.(警告)4)表示可能或一定会发生某种情况。例如:I am sure he is to succeed next time.符合第二条...