| A single rocket is not powerful enough
to send a spaceship into space. This is because all the fuel a single rocket
can. carry is not enough to give the necessary amount of power. To get enough
fuel and power to last till the spaceship gets out of the Earth’s gravitation
force (引力) , a number of rockets are needed. These rockets are connected one on
top of the other, looking much like a large tower. Together they form a
multi-stage rocket. The spaceship lies at the top of the multi-stage
rocket. The first stage of a multi-stage rocket is called the booster. It is the biggest as it has to lift the whole thing from the ground. The booster helps to lift the rockets into the sky. When the fuel of the booster is used up, it separates from the rest of the rocket and drops to the Earth. When this happens, the second stage fires and pushes the rocket A. The booster B. The second rocket C. The third rocket D. The multi-stage rocket [单项选择]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 (76) powerful enough to shoot astronauts (77) the earth’s gravitational pull and (78) them on the moon. We have now become (79) in space.
Impressive and complex (80) it may appear, the rocket, which was (81) in China over 800 years (82) , is a relatively simple device. Fuel that is (83) in the rocket engine changes (84) gas. The hot and rapidly (85) 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. A. heating B. escaping C. expanding D. conducting 我来回答: 提交
|
