[填空题]Because light travels (fast) ______ than sound, lightning is seen before thunder is heard.

[填空题]Because light travels (fast)______ than sound, lightning is seen before thunder(雷) is heard.

[填空题]Due to the fact that light travels______(fast)than sound,lightning is seen beforethunder is heard．

[单项选择]
The Docklands Light Railway (DLR) took just three years to build at a cost of ￡77 million. It is London’s first Light Rail System, but its route follows that of a number of older lines, which carried the nineteenth century railways through the crowed districts of the East End.
The section of the line from the Tower Gateway Station to Poplar follows the line of one of London’s earliest railways, the London & Blackwell (1840), a cable-drawn railway (later converted to steam) which carried passengers to steam ships at Blackwell Pier, and provided transport for the messengers and clerks who went backwards and forwards between the docks (码头) and the city every day.
From Poplar to Island Gardens, a new line crosses high above the dock waters, and then joins the old track of the Millwall Extension Railway, built to service the Millwall Docks (1868) and to provide transport for workers in the local facto
A. was constructed in the nineteenth century.
B. will be finished in three years’ time.
C. follows some of the original lines.
D. took three years longer than expected to complete.

[单项选择]Light travels very fast. It moves at a speed of 300,000 kilometers a second. Light reaches us from the moon in less than a second and a half. The moon is about 382,000 kilometers away.
Light from the sun reaches us in 8.5 minutes. The sun is about 149,840,000 kilometers from the earth.
The other stars are farther away than the sun. Light from the nearest star reaches us in about four years. When you look at a star, you do not see its present condition. You see it as it used to be. Light from some stars takes hundreds of years to reach us. We never see a star as it is now. We see it as it was long ago; perhaps hundreds of thousands of years ago.
Astronomers (天文学家) watch the stars through big telescopes. The world’s biggest telescope is in Russia. The next biggest is in-the United States. With these great telescopes astronomers can see stars and other things very far away. Some of these things are not only stars. They are great groups of stars.
The earth is nearer to __
A. the stars... the sun
B. the moon... the sun
C. the stars... the moon
D. the sun... the moon