（2014山东省实验中学高三第二次模拟考试）6．Jack and Samantha ____________ for their wedding for a whole week but nothing is really done．
A．have prepared
B．are prepared
C．have been preparing
D．prepared
答案：C
句义：Jack 和 Samantha为他们的婚礼准备了一个星期，但是什么都没有准备好。本句的关键词是for a whole week，该时间状语通常都是很现在完成时连用，表示从过去某个时间开始到现在一直都在做的事情，强调动作的持续性和反复性。故C正确。
| The sun today is a yellow dwarf star. It is fueled by thermonuclear reactions near its center that convert hydrogen to helium. The sun has existed in its present state for about 4 billion, 600 million years and is thousands of times larger than the Earth. By studying other stars, astronomers can predict what the rest of the sun’s life will be like. About 5 billion years from now, the core of the sun will shrink and become hotter. The surface temperature will fail. The higher temperature of the center will increase the rate of thermonuclear reactions. The outer regions of the sun will expand approximately 35 million miles, about the distance to mercury, which is the closest planet to the sun. The sun will then be a red giant star. Temperatures on the earth will become too hot for life to exist. Once the sun has used up its thermonuclear energy as a red giant, it will begin to shrink. After it shrinks to the size of the earth, it will become a white dwarf star. The sun may throw off huge amounts of gases in violent eruptions called nova explosions as it changes from a red giant to a white dwarf. After billions of years as a white dwarf, the Sun will have used up all its fuel and will have lost its heat. Such a star is called a black dwarf. After the Sun has become a black dwarf, the earth will be dark and cold. If any atmosphere remains there, it will have frozen onto the earth’s surface. |
The phrase "throw off" underlined in Paragraph 3 most probably means ______ .
A．eject
B．burn up
C．convert
D．let in