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【C11】______an opening that【C12】______backward. As the gas is【C13】______with great force, it【C14】______the rocket in the【C15】______direction. Like the kick of a gun【C16】______it is fired, it【C17】______the laws of nature【C18】______by Sir Isaac Newton when he discovered that"【C19】______every action, there is【C20】______equal and opposite reaction."

【C1】

A．shown

B．been

C．appeared

D．proved

impressive symbol of the new space age. Rocket engines have 【C1】______ powerful enough to shoot astronauts 【C2】______ the earth's gravitational pull and land them on the moon. We have now become space 【C3】______ .

Impressive and complex as it may appear, the rocket, which was 【C4】______ in China over 800 years ago, is a relatively simple device. Fuel that is 【C5】______ in the rocket engine changes 【C6】______ gas. The hot and rapidly 【C7】______ gas must escape, but it can do so only through an opening that 【C8】______ backward. As the gas is 【C9】______ with great force, it 【C10】______ the rocket in the 【C11】______ direction. Like the kick of a gun 【C12】______ it is fired, it 【C13】______ the laws of nature 【C14】______ by Sir Isaac Newton when he discovered that" 【C15】______ every action, there is an equal and opposite reaction."

【C1】______

A．shown

B．been

C．appeared

D．proved

What kind of engine did the Hyper-X use？

A．A jet engine that carries its own oxygen supply.

B．A jet engine that uses no oxygen.

C．A scramjet engine that doesn't carry its own oxygen supply.

D．A rocket engine that carries its own oxygen supply.

32 What kind of engine did the Hyper-X use？

A A jet engine that carries its own oxygen supply．

B A jet engine that uses no oxygen．

C A scramjet engine that doesn't carry its own oxygen supply．

D A rocket engine that carries its own oxygen supply.

What kind of engine did the Hyper-X use？

A．A jet engine that carries its own oxygen supply.

B．A jet engine that uses no oxygen.

C．A scramjet engine that doesn't carry its own oxygen supply.

D．A rocket engine that carries its own oxygen supply.

What kind of an engine did the Hyper-X use？

A．A jet engine that gets oxygen from the air.

B．A scramjet engine that doesn't carry its own oxygen supply.

C．A rocket engine that carries its own supply of oxygen.

D．A jet engine that uses no oxygen.

What kind of an engine did the Hyper X use？

A．A jet engine that gets oxygen from the air．

B．A scramjet engine that doesn’t carry its own 0xygen supply.

C．A rocket engine that carries its own supply of 0xygen．

D．A jet engine that uses no oxygen．