过去发生或已经完成的动作对现在造成的影响或结果,或从过去已经开始,持续到现在的动作或状态
时间状语:recently, lately, since.for.,in the past few years, already ,yet ,never ,ever, just, before, so far ,once, twice etc
.基本结构: have/has + done否定形式: have/has + not +done.
一般疑问句: 把 have 或 has 放于句首。反义疑问句: 直接用 has /have 进行反问
与时间段连用时,短暂性动词应改为相应的延续性动词。
go out----be out finish-----be over leave ----be away from buy ----have borrow
lend -----keepopen ---be open close---be closed die---dead start
begin ----be on join—--be in /be a member of
be a soldier become –be make friend ---be friend get up ---be up fall
asleep ---be asleep catch a cold – have a cold reach/get/arrive---stay/be