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【简答题】
某同学利用打点计时器所记录的纸带来研究做匀变速直线运动小车的运动情况,实验中获得一条纸带,如图所示,其中两相邻计数点间有四个点未画出。已知所用电源的频率为 50HZ ,则打 A 点时小车运动的速度 v A =_______m/s ,小车运动的加速度 a =_______m/s 2 。(结果要求保留三位有效数字)
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皮皮学刷刷变学霸
举一反三
【简答题】图样中的图形只能表达零件的 ,零件的真实大小应以图样上所注的 为依据。
【单选题】When a country takes a multilateral approach to free trade, it
A.
removes trade restrictions on its own.
B.
reduces its trade restrictions while other countries do the same.
C.
does not remove trade restrictions no matter what other countries do.
D.
is willing to trade with multiple countries at once.
【单选题】设变量x，y满足约束条件 x-y+2≥0 x-5y+10≤0 x+y-8≤0 ，则目标函数z=3x-4y的最大值和最小值分别为（ ）
A.
3，-11
B.
-3，-11
C.
11，-3
D.
11，3
【单选题】When trade takes place:
A.
both parties will probably be worse off.
B.
one party must gain at the other party's expense.
C.
both parties can be better off.
D.
one party will gain and the other party will be neither better nor worse off.
【单选题】When a country takes a unilateral approach to free trade, it
A.
removes trade restrictions on its own.
B.
reduces its trade restrictions while other countries do the same.
C.
does not remove trade restrictions no matter what other countries do.
D.
is willing to trade with multiple countries at once.
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