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语态 - 大学英语四级语法精要

语态 可以有两种被动结构的类型,例如:

he was said to be jealous of her success.
it was said that he was jealous of her success.

能同时适用于上述两个句型的主动词通常都是表示“估计”,“相信”等意义的动词,常见的有assume,believe,expect,fear,feel,know,presume,report,say,suppose,understand等.
it is supposed that the ship has been sunk.
the ship is supposed to have been sunk.

担当be supposed to 与不定式的一般形式搭配时往往表示不同的意义.例如:
why are you driving so fast in this area? you are supposed to know the speed to know the speed limit. (你应该晓得速度限制)