界内球的英文：
fair ball

参考例句：

he reached into his inside jacket pocket; inside out; an inside pitch is between home plate and the batter.
他把手伸向衣服的内口袋；里面翻到外面；界内球是在本垒和击球手之间的球。

fair是什么意思：
adj. 公正的；公平的；合理的；白皙的；晴朗的；美丽的
adv. 公平地，公正地；正面地，直接地；清楚地
n. 美人；美好的事物；集市；交易会，展览会；博览会
v. 转晴

They are going to the fair.
他们正在到集市上去。

Welcome you to the fair.
欢迎您到交易会来。

His knowledge of English is fair.
他的英语水平尚可。

hold a fair to raise money
举办义卖会筹款

The elections were free and fair.
选举是自由公正的。

ball是什么意思：
n. 球；舞会
v. 成团块；捏成球形

You have no balls!
你们一点胆量都没！

The kitten tangled the ball of yarn.
猫把线团儿弄乱了。

A ball hissed by.
子弹嘶地一声飞过。

The dog had itself a ball.
狗玩得很愉快。

Do you have the balls to challenge authority?
你有挑战权威的胆量么？