沉降过滤式离心机工作工作过程？

Fireworks exploded during _____ opening ceremony of _____ 2011 Asian Cup football tournament at Khalifa Stadium．

A．the; a

B．the: the

C．a; a

D．a; the

I wonder why Jack always gets good marks when he does only ________ the others.

A．half as much as

B．as much as half

C．half as many as

D．as many as half

亚甲基蓝分光光度法测定水中硫化物时，样品采集很关键，简述采样过程。

如图所示，将质量为3.5kg的小球水平抛出，g取10m/s²，空气阻力不计。求：

（1）抛出时人对球所做的功？

（2）抛出后0.2秒时小球的动能？

根据片区现有写字楼客户调查分析，将非主流行业、非主流来源区域的企业以及在非投资过热时期的纯投资型客户作为( )。

A．核心客户群锁定
B．重要客户群锁定
C．游离客户群界定
D．散户群客户锁定