发声物体单位时间内振动的次数叫_________，声源振动的_________决

铅箔增感屏中起吸收软射线作用的是（）。

A.前屏

B.后屏

C.没有任何区别

D.以上都不对

为鼓励节约用水，对居民生活用水实行阶梯式计算水价．第一级水量核定为每户每月0吨至18吨（含18吨），价格为每吨1.2元；第二级水量核定这每户每月18吨至25吨（含25吨），价格为每吨1.8元；每户每月用水量25吨以上的为第三级水量，价格为每吨2.4元．

阶梯式计量水价计算公式如下：阶梯式计量水价=第一级水价×第一级水量基数+第二级水价×第二级水量基数+第三级水价×第三级水量基数．

（1）如果5月份甲户用水量为23吨，该户应交水费多少元？

（2）如果5月份乙户应交水费51元，那么其用水量是多少吨？

下列哪些病理类型隶属于增生性肾炎（）

A.局灶性节段性肾小球肾炎

B.系膜增生性肾小球肾炎

C.系膜毛细血管性肾小球肾炎

D.新月体和坏死性肾小球肾炎

E.毛细血管内增生性肾小球肾炎

(a) Aminah saw an advertisement in a newspaper, which referred to a ‘special offer while stocks last’ by a local supermarket of a well-known brand of vacuum cleaners. The offer price was stated to be RM100 per unit. The usual price of such vacuum cleaners was around RM300 per unit. Aminah rushed to the supermarket, chose one of the vacuum cleaners and took it to the payment counter. The salesperson at the counter told her that the supermarket had increased the price of the vacuum cleaner and that the new price was RM320. Aminah refused to buy the vacuum cleaner at that price. She seeks your advice whether the supermarket is contractually bound to sell the vacuum cleaner to her at the advertised price of RM100.Required:Advise Aminah. (5 marks)

1929~1933年经济危机爆发，主要资本主义国家均采取了一系列的反危机措施，下列对这些反危机措施的共同点的评价正确的是

A．发动对外战争转嫁危机

B．采取国家干预的办法，维护垄断资产阶级的利益

C．建立独裁制度，实行国民经济军事化

D．缓和与殖民地的矛盾，倾销过剩商品