题目

----May  I _______ you  to carry the bag for me ? ----- No problem .          A． force   B.trouble    C.question    D.invite  答案：B—A number of students_____ in the dining hall.     —Let me count.  The number of the students _____ about 400.    A. are, is       B. are, are     C. is, are      D. is. is