【单选题】【消耗次数：1】
平移刚体上点的运动轨迹，
①
必为直线；
②
必为平面曲线；
③
不可能是空间曲线；
④
可能是空间曲线。
参考答案：
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【简答题】
证明：平面曲线的挠率为零
随机题目
【单选题】
下列有关合伙企业出资不合法的是：（）
①
普通合伙人甲的一辆汽车的使用权
②
普通合伙人乙的专利权没有评估作价，且约定了乙仍然在原有范围内继续使用该专利
③
有限合伙人出资的专利权没有评估作价
④
普通合伙人李某（犯贪污罪服刑完毕未满1年者）的劳务
【单选题】
The medical officer was praised (表扬) for _______________ the life of a child.
①
saving
②
checking
③
discussing
④
weeping
【单选题】
Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight（困境）while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump（垃圾场）was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump.Why was the goat-keeper chosen to remove the bushes?
①
Because he offered to do it for the lower price.
②
Because it was easier to transport his goats.
③
Because his goats can do the job better.
④
Because the city wanted to raise more goats.
【单选题】
The president has an ____________ secretary.
①
extensive
②
efficient
③
effective
④
expensive