下图是某河流的部分河段，据图分析回答1～3题。 1．河中有沙金，淘金处可能在 ( ) A．① B．②
下表分别给出了一些物质的密度、熔点、比热容，某同学给出的下列结论正确的是 物质密度/（kg/m3） （常温、常压下）物质熔点/℃ （标准大气压）物
－ Is your father in? － No, he ______ for three hours. A. was out B. has been out C. went out D. has gone out
. There is no doubt that adults, and even highly educated adults, vary greatly in the speed and efficiency of their reading. Some proceed very lowly throughout; others dash along too quickly and then
老师让同学们讨论网上购物 (Internet shopping) 的利（advantages）与弊（disadvantages），根据下列信息，请你代表你们组做个发言。（15分） 好处：方便(conven
－Can we ask Uncle Bill for help? －Sorry. He is _______ old to do anything. A. so B. too C. very D. rather
在容积可变的密闭容器中存在如下反应：CO(g)+H2O(g)CO2(g)+H2(g) ΔH<0，下列对图像的分析中不正确的是 A. 图Ⅰ研究的是t0时升高温度对反应速率的影响B.
常温下，某溶液中由水电离产生的c(H+)、c(OH－)满足c(H+)·c(OH－)=10－24，则下列各组离子在该溶液中一定大量共存的是：
，则x的取值范围是______．