关于船舶的摇荡运动,以下说法错误的是()。 ①摇荡运动一定是周期性的往复运动 ②摇荡运动一定是周期性的往复直线运动 ③摇荡运动一定是周期性的往复摇摆运动 ④摇荡运动不一定是周期性的往复运动
A. ①③④
B. ①②④
C. ①②③
D. ②③④
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Moderate Earthquake Strikes England A moderate earthquake struck parts of southeast England on 28 April 2007, toppling chimneys from houses and rousing residents from their beds. Several thousand people were left without power in Kent County. One woman suffered minor head and neck injuries. "It felt as if the whole house was being slid across like a fun-fair ride," said the woman. The British Geological Survey said the 4. 3-magnitude quake struck at 8:19 a.m. and was centered under the English Channel, about 8.5 miles south of Dover and near the entrance to the Channel Tunnel. Witnesses said cracks appeared in walls and chimneys collapsed across the county. Residents said the tremor had lasted for about 10 to 15 seconds. "I was lying in bed and it felt as if someone had just got up from bed next to me." said Hendrick van Eck, 27, of Canterbury about 60 miles southeast of London. "I then heard the sound of cracking, and it was getting heavier and heavier. It felt as if someone was at the end of my bed hopping up and down." There are thousands of moderate quakes on this scale around the world each year, but they are rare in Britain. The April 28 quake was the strongest in Britain since 2002 when a 4.8-magnitude quake struck the central England city of Birmingham. The country's strongest earthquake took place in the North Sea in 1931, measuring 6.1 on the Richter scale. British Geological Survey scientist Roger Musson said the quake took place on 28 April in an area that had seen several of the biggest earthquakes ever to strike Britain, including one in 1580 that caused damage in London and was felt in France. Musson predicted that it was only a matter of time before another earthquake struck this part of England. However, people should not be scared too much by this prediction, Musson said, as the modern earthquake warning system of Britain should be able to detect a forthcoming quake and announce it several hours before it takes place. This would allow time for people to evacuate and reduce damage to the minimum. During the April 28 earthquake, the whole England was left without power.()
A. Right
B. Wrong
C. Not mentioned
孔顶应埋设钢护筒,其埋深应不小于()。不得超负荷进钻。
A. 0.2m
B. 0.5m
C. 0.8m
D. 1m
不变资本和可变资本划分的依据是资本在()。
A. 生产过程中不同的价值转移方式
B. 生产过程中不同的物质存在形态
C. 剩余价值生产中的不同作用
D. 周转过程中不同的运动速度