— Is John coming by train ? — He should but he not. He likes driving his car. A. mustB.

问题补充：

— Is John coming by train ?

— He should, but he not. He likes driving his car.

A. must

B. can

C. need

D. may

答案：

A. must

B. can

C. need

(答案→)D. may

解析：先确定问句为将来时态，因为像come,go,leave,start等等这类趋向动词的进行时表示将来时。这是至关重要的，因为答语是就一将来的动作作出判断的。先排除A项，must not译为“不准”，与文意不合；再排除B项，至少cannnot不可分开写；最后排除C项， need not译为“不必”，与文意相左；只有选D项，译为“可能不，不一定”，正好与后文的He likes driving his car相吻合，故应选D项。