题目内容：

she has to clean all the furniture in all the bedrooms in two hours
这句话当中的furniture和bedrooms 为什么一个要加s一个不用加s的?
The young students like dickens' and Mark Twain's novels very much
这句话当中的人名dickens'和Mark Twain's 的s用法为什么不一样的?
I have a lot of work to do
为什么要用a lot of 用many work 不行吗?还有就是那个work后面不能加s的?