.People in developed countries are supposed ______ more healthy food before than what they have today.

A．to be had

B．to have

C．had

D．to have had

1937年7月7日晚，日军在__________附近举行军事演习。日军借口__________，无理要求进入宛平县城搜查，遭到中国守军拒绝，日军悍然向__________中国守军发起进攻，并炮轰宛平城。这就是__________事变，又称__________。__________从此爆发。