Arriving home, she started with math. She had always been a good math student, but now she was         . [ ]

A. struggling

B. improving

C. working

D. complaining

二战结束后，美国的霸权主义政策表现为两种形式，在欧洲是“冷战”，在亚洲是“热战”。战后，美苏之间的“冷战”对抗并未真正爆发大战，其主要原因是[ ]

A．美苏双方势均力敌

B．双方合作多于对抗

C．各国反战运动高涨

D．霸权主义受到遏制