much是一个修饰不可数名词的形容词
eg:There is much water in the glass,玻璃杯里有很多水,水是不可数,所以用much修饰,系动词统一用单数.
如果是修饰可数名次,则用many
eg：There are many people in the room.房间里有很多人.人是可数,所以用many修饰,而且人可数,所以系动词用的是are.
more是much 和many的比较级
eg：There are more people in this room than that one.这个屋子的人比那个屋子的人多
eg：There is more water in this glass than that one.这个杯子里的水比那个杯子的水多