Most electronic devices of this kind, _______ manufactured for such purpose, are tightly packed.  [ ]

A. that are

B. as are

C. which is

D. it is

用氯化钠固体配制一定质量分数的氯化钠溶液，必须使用的一组仪器是（　　）

A．天平、烧杯、量筒、铁架台、药匙、滴管

B．天平、烧杯、漏斗、蒸发皿、玻璃棒、滴管

C．天平、烧杯、量筒、玻璃棒、药匙、滴管

D．天平、集气瓶、漏斗、蒸发皿、玻璃棒、滴管