题目

第二节：语法填空（共10小题；每小题1.5分, 满分15分） If you walked past the supermarket, you would find many foods that have been treated ____16______ (kill) any harmful germs that might have been in them. Milk is a good example. Raw milk --- that is, milk just as it comes from the cow --- may be _____17_____    (safe) to drink. But ____18______ the milk is heated and then cooled, the harmful germs are killed. The man ____19______discovered this way of treating milk was a Frenchman by the name of Louis Pasteur. In the supermarket you would also find many frozen foods ---爱因斯坦的光子论认为 [　　] A．光是能量不连续的一份一份光子在空间的高速传播，每个光子的能量与光的频率成正比 B．光子入射到金属表面时，其能量可被金属中某一个电子全部吸收，并有一部分立即转化为电子的动能 C．金属表面的电子要从金属逸出，必须克服金属原子核引力作一份功，因而发生光电效应的条件是：入射光子的能量大于这份功 D．一定频率的光照射金属时，若有电子逸出，则每个电子离开金属表面时必须有同样大小的动能