Two tennis balls；
他每天下午练两个小时网球/钢琴。
He practised tennis/ the piano for two hours every day.
扩展资料
他亲自教两个女儿打网球，并且教得很好。
He taught them how to play the game and he taught them well.
女性1900年首次参加奥运会，当时她们只参加两个项目&网球和高尔夫。
Women made their Olympic debut at the Paris Games in1900, only two sports were open to them-tennis and golf.
学校两个最棒的`网球选手之间的竞争很激烈。
There is a lot of competition between the two best tennis players in the school.
爱尔西亚·吉布森是一位非裔美国女性，她不仅仅在一个领域，而是在两个体育领域：网球和高尔夫，都取得了卓越的成就。
Althea Gibson was an African-American woman who achieved greatness in not one, but two sports: tennis and golf.
