下列气的作用，能维持人体正常体温恒定的是A．推动 B．温煦 C．防御 D．同摄 E．

补全对话。

1. A: Is Danny a good piano _________?  

    B: No, _________.  

2. A: _________ does Steven play the piano?       

    B: Once a week.      

3. A: Can you play the erhu?       

    B: _________, I can't.

When I try to understand _______ that prevents so many Americans from being as happy as one might expect, it seems to me that there are two causes.

A．why it does

B．what it does

C．what it is

D．why it is

我国古建筑单体外形的特点可概括为“高基座、木构架、大屋顶”，大屋顶是决定建筑单体结构的核心。( )P104

对以保健食品名义报检的进口食品，检验检疫机构根据卫生部保健食品批号即可签发《卫生证书》 ( )

T•JK2、T•JK2－A型车辆减速器的工作风缸由哪些部件组成？