(2)现在完成时的第二个基本用法表示过去已经开始，持续到现在的动作或状态。该用法常和表示过去某一时刻延续到现在的一段时间的状语连用。

①与for +一段时间连用，表示多久。

e.g. He has learned English for two years.他已经学习两年英语了。

I have been here for three days.我在这里已经3天了。

②与since +时间(起点)连用，表示自…以来。

e.g. His father has worked in that factory since 1991.他爸爸自1991年以来都在这家工厂工作。

I’ve had a cold since last Friday.自上星期五起我就感冒了。

③与since +一段时间+ ago连用，表示自…以前就…。

e.g. Jim has waited there since half an hour ago.吉姆自半个小时前就已经在那里等候了。

He has stayed here since three weeks ago.他在这儿已呆了三个星期。

④与since +从句(从句用一般过去时)连用，表示自某事发生后就一直…。

e.g.The Greens have lived in Beijng since they came to China.格林一家自从来到中国后就一直住在北京。

I’ve known her since I came to work here.自从我来这里工作就认识他了。