dǎ / wǎngqiú / de / shíhòu / yào / xuǎn / shìhé / zìjǐ / de / pāi / zi / , / cái / néng / fāhuī / chū / zuìhǎo / shuǐpíng / .

打网球的时候要选适合自己的拍子，才能发挥出最好水平。

You should choose a racket that suits you when playing tennis to perform at your best.