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问题 多选题

a、b两物体在t=0时刻沿同一直线开始运动，为了定量描述它们的运动情况，建立了一直线坐标系，如图甲所示．它们的位置坐标随时间的变化关系如图乙所示，则下列说法中正确的是（　　）

A．a、b两物体的出发点相同

B．t=2s时a的速度大于b的速度

C．a、b两物体的运动方向相同

D．0-6s内a通过的位移大于b通过的位移

答案

A、由图可知，两物体均从原点正方向5m处开始运动，故出发点相同，A正确；

B、两物体均做匀速直线运动，a的斜率小于b的斜率，所以a的速度一直小于b的速度，故B错误；

C、ab两物体均从5m处向原点运动，故运动方向相同，故C正确；

D、由图可知，6s内a的位移为3-5=-2m； b的位移为1-5=-4m；故b的位移大于a的位移，故D错误；

故选AC．

单项选择题

实施阶段项目决策咨询业务内容包括( )。

A．监测与绩效评价

B．工程监理

C．项目监测评价

D．合同管理
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单项选择题

Even plants can run a fever, especially when they are under attack by insects or disease. But (1) humans, plants can have their temperature (2) from 3,000 feet away—straight up. A decade ago, (3) the infrared scanning technology developed for military purpose and other satellites, physicist Stephen Paley (4) a quick way to take the temperature of crops to determine (5) ones are under stress. The goal was to let farmer (6) target pesticide spraying (7) rain poison on a whole field, which (8) include plants that don’t have the pest problem.

Even better, Paley’s Remote Scanning Services Company could detect crop problem before they became (9) to the eye. Mounted on a plane flown at 3,000 feet (10) , an infrared scanner measured the heat emitted by crops. The data were (11) into a color-coded map showing (12) plants were running "fevers". Farmers could then spot spray, using 50 to 70 percent less pesticide than they (13) would.

The bad news is that Paley’s company closed down in 1984, after only three years. Farmers (14) the new technology and long-term backers were hard (15) . But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to (16) into operation. Agriculture experts have no doubt about the technology works. "This technique can be used (17) 75 percent of agricultural land in the United States," says George Oerther of Texas A＆M. Ray Jackson, who recently retired from the Department of Agriculture, thinks (18) infrared crop scanning could be adopted by the end of the decade. But (19) Paley finds the financial backing (20) he failed to obtain 10 years ago.

5（）

A.whose

B.which

C.what

D.where
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