对于共源性暴发（） A.不能用潜伏期来推算暴露日期或时间范围 B.从流行曲线的尾部向

The brave people in the village preferred to die rather than _____ , and _____encouraged others to fight more bravely in the anti-Japanese battlefield.

A．to give in ; it

B．to give in; which

C．give in ; this

D．give in ; which

短文改错。

     Last summer I learnt to ride a bicycle. At first,I was unable to control it's direction. Sometimes

I fall to the right or to the left. But I asked my father to tell me how I could ride straightly. He didn't

answer me directly. Instead, he took me to side of the street. "Can you find some bike track that is

really straight?" asked my father. I watched more carefully and shook my head ."No" he said, "in fact

neither of the tracks is always straight. But just by correct the direction every now and then, you had

already gone forward."

核心系统对私凭证的支付条件为（）的，才可以在规定的范围内办理通存通兑。

A.凭单折；

B.凭密码；

C.凭证件；

D.凭交易密码加证件；

E.凭印鉴

关于重链病的错误叙述（）

A.血清电泳可见M蛋白区带

B.重链病一般无本-周蛋白尿

C.易反复感染

D.属一种良性病变

E.常见的是γ、α和μ型重链病

影响锅炉热效率的主要因素有哪些？运行中如何提高锅炉的热效率？