评价某6岁男童的身高是否正常，宜采用（） A.点估计 B.区间估计 C.假设检验 D

Peter, can you come downstairs and do me a favor?

Yes, mum. I ______.

A. came              B. come                C. am coming

2011年3月由财政部代理发行的2000亿地方债券上市，各地居民竞相购买。同其他债券相比，地方债券[ ]

A．代用率高、流通性好

B．风险最小、安全性最小

C．收益最高

D．转手不易

He hesitated for a moment before he kicked the ball, otherwise we ______ the game. Such was the case.[ ]

A. had won

B. won

C. would win

D. would have won

下列哪种营养素不易通过乳腺输送到乳汁中（）

A.铁

B.钙

C.维生素A

D.维生素C

E.维生素E

试论述气体中硫氧化物的控制技术。