下面哪项不是不溶性阳极电镀工艺的主要特征设备（）。A、锡离子浓度计 B、过滤器 C、

Look, There’s __________ sheep on the hill and there are _______ children, too.

A．a few; a few

B．a ; a few

C．a few; a little

D．a little; a little

由我国著名化工实业家吴蕴初先生创办的上海天原化工厂，目前生产的液氯含氯99.6%，含水分小于0.05%，在化工生产中这种液氯可看做[ ]

A. 纯净物

B. 混合物

C. 化合物

D. 单质

— Mom, the door ____. My keys are locked in it again.

— You ____ it! I told you always to carry your keys with you. [ ]

A. can't open; have asked for

B. wouldn't be opened; asked for

C. won't open; asked for

D. can't be opened; are asking for

A-S反应的组织学特征

骑自行车在校内哪些地段应下车推行？