I have lost my pen.
I have hurt myself.
He has become a teacher.
She has broken my heart.
句型变化：
★变疑问句将助动词移到句首，变否定句在助动词后面加not.
e.g. Have you lost your pen? I have not lost my pen.
★肯定回答及否定回答
Yes, I have. No, I have not.
★特殊疑问句：
What have you done?
What has he done?
一般过去时与现在完成时的区别：
凡是有明确的表示过去的时间状语的句子为过去时
注意：有些动词表示的动作有一个终点，不能再延续，因此不能和表示一段时间状语连用
错：I’ve left Beijing for 3 days.
对：I left Beijing 3 days ago. I have been away from being for 3 days.
过去完成时
用法：在过去的时间里，两个动作中，发生在前的那个动作要用过去完成时。
结构：had+过去分词
After she had finished her homework, she went shopping.
They had sold the car before I asked the price.
The train had left before I arrived at the station.
After/before引导的时间状语从句放在句首要在句子后面加逗号，如果放在主句后则不用加。
1.变疑问句将助动词移到句首
Had she finished her homework?
2. 变否定句在助动词后面加not
She hadn’t finished her homework.
3. 肯定回答及否定回答
Yes, she had. No, she hadn’t.
4.特殊疑问句：
What had she done?