The rocket engine, with its steady roar like that of a waterfall or a thunde

游客2024-01-18  15

问题     The rocket engine, with its steady roar like that of a waterfall or a thunderstorm, is an impressive symbol of the new space age. Rocket engines have【C1】______powerful enough to shoot astronauts【C2】______the earth’s gravitational pull and【C3】______them on the moon. We have now become【C4】______in space.
    Impressive and complex【C5】______it may appear, the rocket, which was【C6】______in China over 800 years【C7】______, is a relatively simple device. Fuel that is【C8】______in the rocket engine changes【C9】______gas. The hot and rapidly【C10】______gas must escape, but it can do so only through an opening that faces backward. As the gas is radiated with great force, it pushes the rocket in the opposite direction. [br] 【C1】

选项 A、shown
B、been
C、appeared
D、proved

答案 D

解析 prove证明。因其后接形容词powerful作表语,故应填系动词。shown不是系动词;been和appeared虽可作系动词但与句意不符;而proved可作系动词,意为“证明是”,符合句意。
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