A.一种,for 循环B.两种,for 循环和while 循环C.三种,for 循环、while 循环、do...while 循环
A.```javascript event.stopPropagation;```B.```javascript window.event.cancelBubble=false;```C.```javascript event.stopPropagation();```
A.location 对象包含historyB.window 对象是所有页面内容的根对象C.document 对象包含location 对象