現在完成時轉換成一般過去時

現在完成時可以轉化成一般過去時，還可以轉化成“It is/has been +時間段+since從句(用一般過去時)”等句型。

e.g. Jim has been back for a month. 吉姆已經廻來一個月了。 = Jim came back a month ago. 吉姆一個月前就廻來了

= It is/has been a month since Jim came back. 自吉姆廻來已經有一個月了。 = 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.