表示结果的现在完成时

现在完成时着眼于过去的动作对现在产生的结果或影响。这是现在完成时的“已完成”用法，表示动作或过程发生在说话之前就已完成，并与现在有联系。这种联系实际上就是“过去的动作”对现在的影响或产生的结果。

I have bought a pen.

我买了一支笔。(结果：I have a pen now.)

The temperature has increased by 10℃.

温度上升了10摄氏度。(结果：It is quite hot now.)

Air pollution has taken the lives of many people.

空气污染已经夺去了很多人的生命。(结果：Air pollution is very serious now.)

注意：

现在完成时的上下文所指的时态必须呼应。

【误】I have bought a pen but I have lost it now.(have bought表示你现在已经有笔了，这和后面的have lost有矛盾)

【正】I bought a pen but I have lost it now.

我(过去)买了一支笔，但我已经把它丢了。

【误】I have lost my pen but I have found it now.(have lost强调你现在已经没有笔了，与后面have found的意思有冲突)

【正】I lost my pen but I have found it now.

我丢了一支笔，但现在已经找到了。