大指的英文：
a thumb

thumb是什么意思：
n. 拇指
v. 翻阅；以拇指拨弄；请求搭便车

thumb slide rules
翼形滑尺

There is a hole in the thumb of his mitten.
他的手套的姆指上有个洞。

He caught his thumb in the door.
他的拇指让门夹住了。

The Jones family is under the thumb of the mother.
琼斯一家人都得听从母亲的。

He is a rule-of-thumb photographer.
他是一个靠经验摄影的摄影家。