I was driving home the other day on a sunny afternoon. I had a smile on my face as I sang along to the songs on the radio. It was a beautiful day that I felt full of happiness. My good mood ended,
Soldiers stood next to a police truck, looking at the crime scene _______ a woman was gunned down in a poor neighborhood of the border city of Iran October 18, 2009. A. that
当前世界粮食问题的主要表现有（） A．全球粮食产量严重不足 B．发达国家人均粮食消费量过高，粮食不能自给 C．世界粮食生产的地区分布不均衡 D．
曲终收拨当心画， 。东船西舫悄无言， 。（白居易《琵琶行》）
如图，棱锥P—ABCD的底面ABCD是矩形，PA⊥平面ABCD， PA=AD=2，BD=. （1）求证：BD⊥平面PAC； （2）求二面角P—CD—B余弦值的大小；
(12分)某研究性课题小组的同学对植物生长素非常有兴趣，设计了如下实验：探究单侧光使生长素转移了，还是将生长素分解了？ (1)某同学研究植物向光
如图所示，在以坐标原点O为圆心，半径为R的半圆形区域内，有相互垂直的匀强电场和匀强磁场，磁感应强度为B，磁场方向垂直于xOy平面向里。一带正
You had a good time, ____ you? A.don’t B. hadn’t C. didn’t D. aren’t
