下列观点中不正确的是（ ） A、通过化学变化一定能改变物质的性质 B、人们所使用的材料，都是纯度越高越好 C、
____Lily ___Lucy can go with you , because one of them has to stay here to look after their mother A. Either ; or B. Neither ; nor C. Both ; and D. Not only ; but also
如图所示，两平行金属导轨CD、EF间距为L，与电动势为E的电源相连，质量为m、电阻为R的金属棒ab垂直于导轨放置构成闭合回路，回路平面与水平面成θ
______ the story of our village, an interesting film was made by the famous director. A. Based on B. Basing on C. Be based on D. Being based on
右图为电解水的实验装置图。接通电源观察两电极都有气泡产生。 （1）通电一段时间后，玻璃管a收集到的气体是 ， a、b两玻璃管收集的气体体积比
运用所给单词的正确形式填空 1.We can’t find the differences between these two people_______________(easy). 2. It is important for us (take) action to prevent A-Flu-
下列反应方程式中有一个与其他三个在分类上不同，这个反应是( ) A．S＋O2SO2 B．Na2CO3＋CO2＋H2O===2NaHCO3 C．NH4HCO3NH3↑＋C
