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

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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...

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 tru...

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...