某质点的位移随时间的变化关系式x=4t+2t2,x与t的单位分别是m和s。则该质点的初速度和加速度分别是 （ ） A．4m/s和4m/
She changed so much that I could hardly _______ her when we met again after a separation of 20 years. A. recognize B. know C
回答下列与生物学实验有关的问题： (1)某棉农获知脱落酸可以促进叶片脱落的原理后，采收前在棉田喷施了一定量的脱落酸，试图除去棉花叶片便于机
It was the man______ on the bed with his eyes open who_____the book open on the desk just now. A. lain; lay B.lying ;laid C.lay; lay D.lying ;lied
已知椭圆经过点，且离心率为. （1）求椭圆的方程； （2）设点在轴上的射影为点，过点的直线与椭圆相交于、两点，且，求直线的方程.
Benjamin West, the father of American painting, showed his talent for art when he was only six years of age. But he did not know about brushes before a visitor told him he needed one. In those days,
张先生是某跨国公司中国分公司业务代表，常年在各国奔走。张先生在国内与一家相关公司谈成一笔业务，合同金额6000万元人民币。对方要支付6000万元
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