As is required by their employer, the employees ______ finish the project within this month.
A.could
B.shall
C.may
D.should
答案:D
题目分析:句意:正如雇主的要求,雇员应该在本月内完成该项目。四个情态动词的含义分别是:A. could能够, B. shall应该,C. may可以,D. should应该,从句中用了required,所以主句用should do表示虚拟语气。选D。