基 础 过 关第 3 课时 Section A (Grammar Focus - 4c)单元语法精讲 课 堂 导 学课 堂 导 学☆1
be supposed to do sth
和 be expected to do sth
结构 (1)be supposed to do sth
=be expected to do sth
to 是不定式符号,不是介词,后应接动词原形
常用来表示劝告、建议、 告知义务或责任等,相当于 should
如: You are supposed/expected to ask the teacher if you want to leave the classroom
如果你要离开教室,你应该问问老师
注意:be expected to do sth
比 be supposed to do sth
的主观性更强
如: You're expected to do your duty
你应该恪尽职责
(2)在口语中,常用否定结构“be not supposed to do sth
”,意为“不允许做某事,不应该做某事”
相当于 shouldn't
如: You are not supposed to smoke on the bus
=You shouldn't smoke on the bus
你不应该在公共汽车上吸烟
(3)was/were supposed to do sth
相当于 should have done sth
,表示“(过去)本应该做某事而实际上并没有做”
如: I was supposed to arrive at 7:00, but I arrived at 8:00
我应该 7 点钟到,却 8 点钟才到
(4)suppose+that 从句,当变为否定句时,否