新GRE阅读理解36套每日讨论--33（群178674184）

普渡哥

   Heat pumps circulate a fluid refrigerant that cycles
   alternatively from its liquid phase to its vapor
   phase in a closed loop. The refrigerant, starting as a low-
   temperature, low-pressure vapor, enters a compressor
5 driven by an electric motor. The refrigerant
   leaves the compressor as a hot, dense vapor
   and flows through a heat exchanger called the
   condenser, which transfers heat from the refrigerant to a body of air.
   Now the refrigerant, as a high-pressure, cooled liquid, confronts
10 a flow restriction which causes the pressure to drop. As the pressure
   falls, the refrigerant expands and partially vaporizes,
   becoming chilled. It then passes through a second
   heat exchanger, the evaporator,  which transfers
   heat from the air to the refrigerant, reducing the
15 temperature of this second body of air.
(126 words)


1. According to the passage, the role of the flow
restriction in a heat pump is to
(A) measure accurately the flow rate of the
refrigerant mass at that point
(B) compress and heat the refrigerant vapor
(C) bring about the evaporation and cooling of
refrigerant
(D) exchange heat between the refrigerant and the
air at that point
(E) reverse the direction of refrigerant flow when
needed

jojo888

C~~~~~~

bennyaaron

c???

wyfishhenry

CCC~

普渡哥

确定吗？你们确定是C吗？

bennyaaron

不会都错了吧

普渡哥

恭喜你们，都答对了：）