英语，将下列的两个句子合并成定语从句！

they'll put off the sports meeting till next week if the weather may be better then
it ws not true that she said she had never met him before
i met an old classmate of mine who was very pleased to meet me
一般要加上定语从句连接词 是人 用who 物一般用 what 等 这些语法书上写很多 认真看看

不清楚什么是定语从句（没学过）。就是直接合成一句么？
不过可以合成一句试试
they will put off the sports meeting till next week because the weather may be better then.
she said she had never met him before which it was not true.
i met an old classmate of mine and he was very pleased to meet me too.

你好
they'll put off the sports meeting till next week ,the weather may be better then
合并后是 they'll put off the sports meeting till next week when the weather may be better
she said she had never met him before ,it was not true
合并后是 She said she had never met him before, which was not true.
i met an old classmate of mine ,he was very pleased to meet me,too
合并后是 i met an old classmate of mine who was very pleased to meet me too

方法就是找两句的共同点，（时间？地点？人物？）之后在选择正确的连接词就行了

希望能帮到你~

定语从句（Attributive Clauses）在句中做定语，修饰一个名词或代词，被修饰的名词,词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。
同时定语从句又分为限定性定语从句和非限定性定语从句。
第一句他们将把运动会延迟到下周，理由是下周的天气会更好。
所以是用as引导的非限定性定语从句，即用逗号从中间隔开。
As the weather may be better next week, they will put off the sports meeting till then.
第二句， 她说她以前从来没有见过他，这不是真的。用限定性定语从句。
It was not true that she said she had never met him before.
第三句，我遇到了我一个老同学，他也很高兴见到我。
I met an old classmate of mine who was very pleased to meet me too.
分别用了as,that,who。表示客观事实一般用非限定定语从句，而主观性的一般用限定性定语从句。