题目

用方框中短语的适当形式填空。 win a prize, in a row, help…with, be a volunteer, take a break （1） Sarah in the last speech competition. （2） We want to after working long hours. （3） I'd like because it's a good chance for me to help others. （4） I'd like to say thank you to my friend who always me my study. （5） He tried to throw the ball into the net , but he failed.理论预测以下物质的物理性质，用＞、=、＜填空：（1）CS2的沸点______ CO2的沸点．   （2）CsCl的熔点______KCl的熔点．（3）金属K的硬度______金属Ca的硬度 （4）金刚石的硬度______晶体硅的硬度．