My father ________ to Nanjing twice. A. has been B. has gone C. have been D. have gone
--- An ant has two stomachs --- one for itself, one for others. --- Really? Quite interesting. I ____ anything about it. A. don’t know B. have known C. haven’t known
Watching TV is a very popular pastime in the UK but what kind of programmes do British people like to watch? Well, the most-watched TV programmes every week are very popular dramas that are usually on
（2013•临沂）当你走在放学回家的路上，突然间狂风大作，电闪雷鸣，这时你会急忙找避雨地点，并迅速跑过去．如图是该过程的反射活动图解，请你
如图所示，两颗卫星围绕着质量为M的中心星体做匀速圆周运动．若两颗卫星和中心星体始终在同一直线上，两颗卫星间的作用及其他星体对两颗卫星的
据英国《每日邮报》2008年9月1日报道，最新卫星照片显示，北极在人类历史上首次成为一个岛屿。据此回答下面试题。 要监测北极冰川面积的变化，应
在一个草原生态系统中，最多的生物是 ( ) A．狼 B．禾本科植物 C．羊 D．老鼠
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