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【单选题】
A constant force is exerted on a cart that is initially at rest on an air track. Friction between the cart and the track is negligible. The force acts for a short time interval and gives the cart a certain final speed. To reach the same final speed with a force that is only half as big, the force must be exerted on the cart for a time intervalA.
four times as long as that for the stronger force.
B.
twice as long as that for the stronger force.
C.
equal to that for the stronger force.
D.
half as long as that for the stronger force.
E.
a quarter of that for the stronger force.
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【多选题】拜访与接待语言的基本要求 有哪些?
A.
言之有礼——讲究用语，彬彬有礼
B.
言之有的——紧扣中心，因人施语
C.
言之有物—— 注重话风，不尚空谈
D.
言之有理 —— 合乎逻辑，防止诡辩
【简答题】设计乔木冠幅、花灌木边缘轮廓线,图例线、尺寸线、尺寸界线等用_______(线型)来绘制。