不是。有时可以用a,不可数名词的话前面有时也可以不用。下面我举三个简单的例子让你明白:1)Give me the book which you think is good.把这本你认为好的书给我吧! 2)Give me a book which you think is good .给我一本你认为好的书。 3)give me some bread which you bought just now.给我点你刚买的面包。
不用。复数就不用,有些名词也不用。谢谢!