一个改错题如下：I think friends are those people can help you when y

Correct：I think friends are those people who can help you when you are in trouble。首先这个句子的时态你要搞清楚了。people who can……这是定语从句,做的是people的定语,在定语从句中,who是从句中的主语,help是从句中的谓语动词。这就是个定语从句。你还有什么不明白的。