能消除或减小由试剂.蒸馏水及实验器皿带入的杂质引起的误差的试验是（）。
A.空白试验；
B.对照试验；
C.回收实验
参考答案：A
阅读理解。
一个名为“人口危险委员会”的组织对世界上100个大城市进行了调查。请根据下面12个主要
大城市的调查表回答问题。
1. Of the following cities, people live in spend least of their income on food. [ ]
A. Mexico City
B. Los Angeles
C. Calcutta
D. Bombay
2. The number of the students studying in high schools in Tokyo out of 100 students is the same as
that of . [ ]
A. Seoul
B. St. Paul
D. Osaka
3. In which city do all the houses have water and electricity? [ ]
A. London.
B. Los Angeles.
C. New York.
D. Bombay.
4. It is the most difficult for people in to make a phone call. [ ]
A. St Paul
B. Mexico City
C. Bombay
D. Calcutta
简述土壤矿物的化学风化过程的类型。
