Archery(射箭) may be the oldest sport in the world. There are prehistoric drawings which show that bows and arrows were used 20 000 years ago. In early times, animals were always hunted and killed w
如图,是由四个相同的小正方体组成的立体图形,它的俯视图是( )
质量为m的三角形木楔A置于倾角为的固定斜面上，它与斜面间的动摩擦因数为，一水平力F作用在木楔A的竖直平面上，在力F的推动下，木楔A沿斜面以恒
最容易找到苔藓植物的环境是( )A、向阳潮湿，无污染 B、背阴潮湿，有污染 C、向阳干燥，有污染 D、背阴潮湿，无污染
名著导读。（3分）枪口轻蔑地望着他的眼睛。 把手枪放在膝上，狠狠地骂了起来：“老弟，这是冒牌的英雄主义！干掉自己，任何一个笨蛋，任
He decided to the matter himself． A．look through B.look into C．look after D．look up
The book has been translated into thirty languages since it on the market in 1973. A．had come B．has come C．came D．c
若函数f（x）=﹣x2+x+1在区间（，4）上有极值点，则实数a的取值范围是（ ） A．（2，） B．[2，） C．（，） D．（2，）
与曲线
的交点个数是 ．