I don't have friends who practice speaking English正确吗,为什么.

I don't have friends who practice speaking English正确吗,为什么.

不正确.以who打头的从句修饰friends,动词practice与friends直接相连就变成是朋友要联系英语了,而句子的意思应该是你想找朋友联系英语,因此中间缺个with.
可改成：I have no friends with whom I can practivce English.