Because the process of freezing food consumes energy, many people keep their electric freezers half-empty, using them only to store commercially frozen foods. Yet freezers that are half-empty often consume more energy than they would if they were kept fully stocked.
Which of the following, if true, contributes most to an explanation of the apparent discrepancy described above ？（）

A．A given volume of air in a freezer requires much more energy to be maintained at a temperature below freezing than does an identical volume of frozen food.

B．The more often a freezer’s door is opened, the more energy is required to maintain that freezer’s normal temperature.

C．When unfrozen foods are placed in a freezer, the average temperature of a given volume of air inside that freezer rises temporarily.

D．A person who normally maintains a half-empty freezer can cut energy costs considerably by using a freezer that is 50 percent smaller.

E．An electric freezer can operate efficiently only if chilled air is free to circulate within the freezing compartment.

以下可引起缺氧及二氧化碳潴留的是（）

A.呼吸肌麻痹

B.急性肺栓塞

C.室间隔缺损

D.肺间质纤维化

E.高热