有三种答案
如果是一般情况可以用
Are there any （any 可省略）books in the bag?
如果针对“书包里有许多书吗”提问,则是
Are there many books in the bag?
补充答案
How many birds are there in the tree?
What are they going to have next Sunday?
What is Mike doing?
Does Jack enjoy listening to music?