MP3是一种广泛使用的数字声音格式。下面关于MP3的叙述中，正确的是( )。A．与

— Why don't we go swimming tomorrow? 

— ______. [ ]

A. You're great

B. That's right

C. What a good idea

D. No, I don't

__________ of all was that not a sound could be heard.

A．It frightened us most

B．The thing that most frightened us

C．We were most frightened by

D．What frightened us most

关于我国目前的卫生工作方针不正确的是（）.

A.以城市为中心

B.预防为主

C.中西医并重

D.动员全社会参与

缺铁性贫血的最常见病因是（）

A.慢性胃炎

B.慢性肝病

C.慢性感染

D.慢性溶血

E.慢性失血

大乘佛教和小乘佛教的区别主要表现在哪些方面