843.I am not going to sit here and let her abuse me.I demand that she immediately _____ for what she just said.
A.apologize
B.would apologize
C.apologized
D.must apologize
844.Great efforts to increase increase grain production _____ if food shortages are to be avoided.
A.could be made
B.must be made
C.might be made
D.would be made
843.答案是A;考查虚拟语气。此处demand后接从句，用should+动词原形。
844.答案是B;考查情态动词及短语的用法。解题关键:掌握短语make great efforts to do sth.根据语境，选must be made。
