could be /must be/ should be/would be的区别

题目

could be /must be/ should be/would be的区别

答案

could be可以理解为CAN BE 能够,你有能力去干吗
/must be必须要,不得不做带有命令的口吻
/ should be最好是,提意见,很委婉
/would be可能是,推测的语气
must be也可以表推测