下列游离生物碱水中溶解度最大的为（） A.氧化苦参碱 B.吗啡 C.乌头碱

（）是法律限制开立保函的情况下出现的保函业务的替代品，其实质也是银行对借款人的一种担保行为。

A．备用信用证

B．客户授信额度

C．信用证

D．开立信贷证明

I was surfing the Internet ____ that the Chinese weightlifter Li Ping broke the world record. [ ]

A. when suddenly came the good news

B. while the good news came suddenly

C. when suddenly did the good news come

D. while suddenly came the good news

– A number of students ____ in the dinning hall.

-- Let me count. The number of the students ____ about 400.

A．are, is

B．is, are

C．are, are

D．is, is

西周末期“二王并立”中的两位国君是（）。

A、周穆王和周康王

B、周宣王和周天王

C、周携王和周天王

D、周携王和周宣王