判断下列句子中while的含义：
问题描述：
判断下列句子中while的含义：
1、Jane was dressed in brown while Mary was dressed in blue.
2、While I admit that the problems are difficult,I don't agree that they cannot be solved.
3、He fell asleep while(he was) reading a grammar book.
答
1.而表示比较
2.即使表让步
3.连词表示正在