1. Since Peking Opera is not their specialty and they were trained for only a short period of time, music teachers cannot help students really appreciate the art.

since的四种用法

1) since +过去一个时间点　(如具体的年、月、日期、钟点、1980, last month, half past six)。

We have been missing them since they left here

自从他们离开这里，我们就一直很想念他们。

2) since +一段时间+ ago　

I have been here since five months ago.

五年前我就来这儿了。

3) since +从句　

Great changes have taken place since you left.

你离开后发生了很多变化。

4) It is +一段时间+ since从句　

It’s a long time since he studied English

他好久没学英语了。

2. to create teachers who are qualified to teach Peking Opera.

这是一个定语从句，teacher是先行词，who are qualified to teach Peking Opera这个从句是用于修饰先行词teacher的。这句的意思就是培养能够胜任教授京剧课程。