1.friends前面用are 不用is。

例句：We are friends. 我们是朋友。He is my friend.他是我的朋友。2.英语学习中are is am 属于be动词。例句是I am an English teacher. You are a student. He is clever.3.名词有可数名词和不可数名词。可数名词有复数形式。不可数名词没有复数。