单选题Directions: {{I}}This task is the same as Task 1. The 5 questions
or unfinished statements are numbered 41 to 45. {{/I}}
Placing a satellite into orbit requires a tremendous amount of energy,
which is achieved from multistage rockets burning chemical fuels.
The first stage of a multistage rocket consists of rocket engines that
provide a huge amount of force. The first stage lifts the entire launch
vehicle—with its load of fuel, the rocket body, and the satellite—off the launch
pad (发射台) and into the first part of the flight. After its engines use all their
fuel, the first stage portion of the rocket separates from the rest of the
launch vehicle and falls to the earth. The second stage then
ignites, providing the energy necessary to lift the satellite into orbit. It,
too, then separates from the satellite and any remaining rocket
stages. The rest of the launch depends on the satellite's
mission. And a third rocket stage provides the energy to lift the satellite to
its final orbital altitude. After the satellite has reached the final altitude,
another rocket engine fires and gives the satellite a circular orbit. All
rocket-engine burns occur at a precise moment and last for a precise amount of
time so that the satellite achieves its proper position in space.
In 1990 the United States began launching some satellites from aircraft
flying at high altitudes. This method still requires a rocket-powered launch
vehicle, but because the vehicle does not have to overcome friction with the
thick atmosphere found at low altitudes, much less fuel is needed. However, the
size of the rocket is limited by the size and strength of the aircraft, so only
smaller satellites can be launched this way.
单选题
What is the main idea about the passage?
A. Placing a satellite into orbit.
B. Multistage rockets.
C. Launching some satellites from aircraft.
D. Rocket launching.
【正确答案】
D
【答案解析】文章第一段，是统领全文。第二段注意“The firs stage of a multistage rocket…”结构；第三段注意“The second stage then.”结构；第四段注意“The rest of laugh…”结构；从这些结构(实际上是各段中心思想)和第一段来看，文章中心思想是D(火箭发射)。
单选题
According to the second paragraph, which of the following is NOT true?
A. The first stage of a multistage rocket consists of rocket engines that
provide a large amount of force.
B. The first stage lifts the entire launch vehicle off the launch pad and
into the first part of the flight.
C. After its engines use up its fuel, the first stage part of the rocket
separates from the rest of the launch vehicle and falls to the space.
D. The entire launch vehicle includes its load of fuel, the rocket body, and
the satellite.
【正确答案】
C
【答案解析】这里错误在“…falls to the space”中的“space”一词上，应为“earth”。
单选题
In the sentence "The second stage then ignites, providing the energy
necessary to lift the satellite into orbit.", "ignites" means______.