He have( )his watch.A a look B a look at

B
不过用He have本身就是错误的。。。

Have a look at/take a look at 是一种固定搭配
“看一眼/看一下”

这种用法比较口语话，一般较少出现在书面中

ex: Can I have a look at your newspaper?
可以把你的报纸给我看一下么？

B.
因为look 是不及物动词，后面要有介词at.

此句还可以说成 He take a look at his watch.更加地道，符合英语国家人的说法。

原句有误,应当是He had a look at his watch.

B
have a look at固定搭配, 但谓语动词用错了,应改成has/had.

have a look at 就是look at 的意思不过你好象没有注意时态什么的,楼上已经说清楚了我就不重复了.has 或had.