题目内容
The exact work of ancient astronomers has led to a modern observation --- our days are longer than they used to be. Not that you’d noticed: The new research in the Proceedings of the Royal Society A shows that it takes the Earth a tiny bit longer these days to complete a single rotation (转动) than it did millions of years ago. It’s the kind of stuff that’s measured in milliseconds per century, but those milliseconds add up. Over the last thousands of years, they’d totaled several hours, which the Los Angeles Times puts this way, “If humanity had been measuring time with an atomic clock that started running back in 700 BC, today that clock would read 7 p.m. when the sun is directly overhead rather than noon. The atomic clock won’t lose a second for 15 billion years.” Maybe more remarkable is that the work is the result of a tireless 40-year research into ancient timekeeping records dating back 2,700 years.
Scientists led by Richard Stephenson of the UK’s Durham University have been studying Babylonian clay tablets, Chinese observations made through the use of water clocks, and Arab astronomical records that tracked solar and lunar eclipses(日/月食). “The most astonishing thing about this study is the fact that we have this information at all,” said a geographer not involved in the study. Researchers are still hoping to find observations from the Incas and the Maya, and to fill in their largest hole between 200 and 600 AD, but they’ve measured the Earth’s deceleration at 1.8 milliseconds per day per century. Given the moon’s gravitational effect on our oceans, the discovery that Earth is decelerating isn’t a surprise, notes the Christian Science Monitor, though astronomers had previously estimated a higher rate.
1.Why are days longer than before according to the text?
A. The earth rotates more and more slowly.
B. Humanity has got incorrect timekeeping records.
C. It takes longer for the earth to turn around the sun.
D. The lost milliseconds for centuries are added to our present days.
2.How did researchers come to the conclusion of the study?
A. By resetting the rotating time of the earth.
B. By referring to ancient timekeeping records.
C. By studying the moon’s gravitational effect on the oceans.
D. By measuring time again with an atomic clock.
3.What can we infer about the study from what the geographer said?
A. Geography theory supports the result of the study.
B. The geographer disagrees to the research conclusion.
C. The scientists’ research is meaningless.
D. It’s right to get geographers involved in the study.
4.What is the meaning of the underlined word “deceleration” in Paragraph 2?
A. Evolution. B. Slowdown.
C. Enlargement. D. Development.
