静压管内使用电加温装置的目的是（）。
A.提高仪表指示灵敏度
B.防止全静压管内结冰而堵塞管路
C.提高仪表指示灵敏度及防结冰
参考答案：B
24. The entire cost of South-to-North project will be more than ___ that of the Three Gorges project, which is expected to cost below US $22 billion.
A．double
B．twice as many as
C．twice than
D．as much as twice
易并发充血性心力衰竭（）易并发支气管肺炎（）易并发脑血栓（）
A.房间隔缺损
B.室间隔缺损
C.动脉导管未闭
D.法洛四联症
E.Roger病
