Wind power is an ancient source of energy _________ we may return in the near future.

A． on which

B． by which

C． to which

D． from which

[单选题]Heat energy is a source of power, but （） will cause damage to the engine.A . excessive heatB . insufficient heatC . effective coolingD . high output

[判断题] 英文POWER和POWER SOURCE的意思都是电源。（）A . 正确B . 错误

[试题]TheancientEgyptiansaresupposed_________rocketstothemoon.A．)tosendB)tobesendingC．)tohavesentD)tohavebeensending

[单选题]People of ancient Egypt and Europeans of the Middle Ages ______.A． both worshipped black catsB． both feared black catsC． thought black cats could bring good luckD． felt very different about black cats

[名词解释] 碳源（source ofcarbon）

[名词解释] 氮源（source ofnitrogen）

[单选题]An instrument that indicates wind direction is known as a(n)（）.A . weather vane，wind vane or wind sockB . hydrometerC . hygrometerD . sling psychrometer

[试题]A．ristotle and Plato in ancient Greece wrote about problems of wealth, property, and trade, both of whom were prejudiced against commerce, feeling that to live by trade was undesirable.

[单选题]In ancient times, people rarely travelled _______long distances and most farmers only travelled the local market.A． longer thanB． more thanC． as much asD． as far as

[单选题]It is easy tomisjudge the [strength] of the wind.A.forceB. directionC. temp