母は魚の肉を＿＿＿＿、猫に食べさせた。A．にじんで B．きしんで　 C．むしって

下列关于双氧水（H₂O₂）和水（H₂O）的叙述中不正确的是（　　）

A．它们都由两种元素组成

B．它们的分子中都含有氢分子

C．它们发生分解反应时都产生氧气

D．它们都属于氧化物

. Recently a terrible earthquake happened in Sichuan, ____the people are still suffering.

A．from their effects

B．of which effects

C．of its effects

D．from whose effects

潜水员由水下10m上浮到水下6m时它受到的（　　）

A．压强增大，浮力不变

B．压强减小，浮力减小

C．压强减小，浮力不变

D．压强增大，浮力减小

Passage Two

The value of heat for the preservation of food has been known for thousands of years, but it was not realized until the nineteenth century that a very mild heat treatment far below the boiling point, made liquid foods such as milk keep much longer. The discovery followed the work of the French scientist Louis Pasteur on wine and beer.

The process, called after him "pasteurization", is a carefully controlled mild heat treatment. It was found that the process served two purposes, it prevented the souring of milk, and it destroyed the dangerous disease germs which sometimes occur in this product.

It has long been known to bacteria experts that the tubercle bacillus is the germ in milk which host ply resists heat treatment. To destroy this organism it is necessary to heat milk to about 60 degrees centigrade for 15 minutes, and its destruction has always been taken as a way of testing the efficiency of pasteurization. A heat treatment of this kind destroys about 99 percent of the common bacteria in milk, including nearly all those which cause milk to turn sour.

To ensure the certain destruction of tuberculosis and other disease germs in milk, it must be held at a fixed temperature for a fixed time. In Britain, for example, these conditions were defined-coy law in 1923 as 63-66 degrees centigrade for 30 minutes. This became known as the "holder" process, since the raw milk had to be pumped into a large tank, heated to just over 63 degrees centigrade, held in the tank for half an hour and then pumped out and cooled. This was a slow process and required a very large plant, so scientists worked for many years to produce a simpler, more convenient method, with less large equipment.

The latest method, officially approved in Britain in 1949, is known as the high-temperature-short-time, or H. T. S. T. method. It has now almost entirely replaced the "holder" process. In the H. T. S. T. system, the milk flows continuously through many sections of thin stainless steel pipes, During the process, the milk is held at 72 degrees centigrade for at least 15 seconds then, as it-cools, the heat is used, in part, to raise the temperature of the incoming milk in a device called a "wheat exchanger".

Efficient pasteurization may reduce the bacteria in raw milk from, say, one million to only a few thousand per cubic centimeter. The bacteria left are chemically mostly of the inert type, thatis, they either do not.

According to the passage, the new H. T. S. T. method differs from the " holder" process in （）.

A．higher rate of bacteria destruction

B．different temperature requirements

C．the ease with which it is operated

D．the amount of energy preserved

新物种形成的标志是（）

A.具有一定的形态结构和生理功能

B.产生了地理隔离

C.形成了生殖隔离

D.改变了基因频率