He has letters to deal with. He has to work from morning to night.A. many ofB. a great de

He has letters to deal with. He has to work from morning to night.
A. many of
B. a great deal of
C. masses of
D. the number of

A. many ofB. a great deal of(答案→)C. masses ofD. the number of解析：考查近义词组：句意：他有大量的信要处理，他得从早到晚工作。A项多了of，B. a great deal of修饰不可数名词，C. masses of大量的，可数不可数都可以修饰，D. the number of…的数量，意思不符合，选C。

就是这个解释