503.My stomach _______ me.I thought it was going away,but now it's getting worse and worse.
A.was killing
B.is killing
C.kills
D.killed
504.Don't ring me up between 3 and 4.I ______ an important talk with the boss then.
A.have had
B.have
C.would have
D.will be having
503.答案是B;根据语境，此处指从过去某个时候一直到现在胃疼得厉害。
504.答案是D;此处between 3 and 4明显指将来。
