a mass of =masses of吗?

a mass of =masses of吗? a mass of 怎么用还有masses of ___rock had fallen from the cliff and now blocked the road.A.Masses of B.A great mass of C.A much mass D.A mass of 选哪个,为什么其他的不行.要区别!= =谢谢了 a mass of是什么意思We took _____ pictures of themA> many of B. masses ofc. a large amount of 为什么是用a mass of ? masses of 是不是与a mass of 意思一样 啊,有什么区别吗两个是不是都可以修饰可数和不可数啊,masses of修饰不可数名词时是不是要用单数,那a mass of 呢 mass的具体用法a mass of 和masses of修饰名词作主语时,其后的谓语动词单复数的用法如何?请详细说明. 适当形式填空.A mass of water_____(be)flowing out of the room.Masses of ice_____(be)floating down the river.A mass of people_____(have)already gathered in the theatre.最好说下理由. a mass of 和 masses of的用法 请简洁的表述并举例 其后面的谓语动词是单数还是复数 the mass of 与 a mass of 有啥区别? masses of 与a large number of区别 英语翻译the masses of three student are in the ratio 4:5:8,if their combined mass is 204kg,find the mass of the heaviest student, mass的用法the mass of 和 a mass of 有什么区别？ masses of 和 a mass of 的谓语动词分别是什么（看问题补充）假设谓语动词为A 词组所修饰的名词为B对于masses of 来说 若B为复数可数名词 则A是are 若B为不可数名词 则A是i masses of the test membrane a quantity of ,many of ,masses of ,the number of 的意思及用法 a mass of 的近义词和词性 a mass of是什么意思及用法 Two masses,M and m,are hung over a massless,frictionless pulley as shown below if M>m,what is the downward acceleration of mass M.用字母表示