現(xiàn)在完成時(shí)可以轉(zhuǎn)化成一般過(guò)去時(shí)，還可以轉(zhuǎn)化成“It is/has been +時(shí)間段+since從句(用一般過(guò)去時(shí))”等句型。 e.g. Jim has been back for a month. 吉姆已經(jīng)回來(lái)一個(gè)月了。 = Jim came back a month ago. 吉姆一個(gè)月前就回來(lái)了 = It is/has been a month since Jim came back. 自吉姆回來(lái)已經(jīng)有一個(gè)月了。 = A month has passed since Jim came back. I have kept the book for two days. = I borrowed the book two days ago. = It is / has been two days since I borrowed the book. = Two days has passed since I borrowed the book.