只是【zhǐ shì】
1. just; no more than; not but; simply 2. but ; only
[副]1、仅仅是，不过是 [连]2、但是
他只是一个孩子，别要求太高了。
He is just a kid, so don't ask too much of him.
这套西装很好看，只是贵了些。
The suit looks nice but it's too expensive.
只要【zhǐ yào】
as long as; if only; so as; so far as; so long as
[连]表示具有充分的条件，正句常用“就”、“也”、“都”、“便”相呼应
只要大家有信心，困难总会克服的。
As long as we have confidence, we will overcome the difficulties in the end.
只有【zhǐ yǒu】
1. have to; be forced to 2. no other than; none but; only
[副]1、只好，不得不 [连]2、表示必需的、惟一的条件
这件事我自己搞不定，只有请别人帮忙了。
This issue is beyond me, so I have to ask for help.
只有自己下水，才可能学会游泳。
One can learn to swim only by getting into the water.
要注重实践，别总是纸上谈兵。
中国是世界上最早发明和使用纸张的国家。
人们常用竖起大拇指来表示称赞。
现在时针指向十二点。
关于浪费问题，领导已经指出过多次了。
