题目

甲、乙、丙、丁四种物质在一定的条件下反应，测得反应前后各物质的质量分数如图所示，则有关说法中正确的是（） A . 该反应为分解反应 B . 甲可能是单质 C . 乙一定是这个反应的催化剂 D . 丙、丁两物质变化的质量比为11：4 答案：B根据句意，用所给单词的适当形式填空1.If you have difficulty _________ (learn) English， you can ask for your teacher’s help .2.Our history teacher told us that TaiWan _________ (be) a part of China.3.–What about going shopping at the weekend ， Ningning ？-- The shopping mall is full of people. I’d rather_________ (stay) at home .4.His (decide) to retire surprised all of us .5.His mother got even (thin) after he failed in exam .