光面冷却壁用在炉腹部位。（）

社会主义宏观调控的基本目标______。

A．抑制通货膨胀

B．促进经济结构优化

C．保持经济增长

D．保持经济总量平衡

扑救( )火灾时，切忌用沙土盖压，以免增强爆炸物品的爆炸威力。

A．遇湿易燃物品
B．易燃液体
C．爆炸物品
D．毒害和腐蚀品

普遍优惠制

It is repeatedly claimed that the dumping of nuclear waste poses no threat to people living nearby. If this claim could be made with certainty, there would be no reason for not locating sites in areas of dense population. But the policy of dumping nuclear waste only in the more sparsely populated regions indicates, at the very least, some misgiving about safety on the part of those responsible for policy.
Which one of the following, if true, would most seriously weaken the argument

A．Evacuation plans in the event of an accident could not be guaranteed to work perfectly except where the population is small.

B．In the event of an accident, it is certain that fewer people would be harmed in a sparsely populated than in a densely populated area.

C．Dumping of nuclear waste poses fewer economic and bureaucratic problems in sparsely populated than in densely populated areas.

D．There are dangers associated with chemical waste, and it, too, is dumped away from areas of dense population.

E．(E) Until there is no shred of doubt that nuclear dumps are safe, it makes sense to situate them where they pose the least threat to the public.

以下哪些项是频谱仪和监测接收机的区别（）

A.预选器

B.自动增益控制

C.混频器

D.静噪