题目

现有六种物质：①聚乙烯、②水银、③聚氯乙烯、④甲烷、⑤氮气． 请选择相应物质的序号填空： （1）空气中含量最多的气体 ； （2）最简单的有机物的是 ； （3）医用体温计里的液体 ； （4）能用于包装食品的是 ． 答案：【考点】空气的成分及各成分的体积分数；金属的物理性质及用途；甲烷、乙醇等常见有机物的性质和用途；塑料制品使用的安全． 【分析】根据空气的成分、物质的组成、性质等分析回答 【解答】解：（1）空气中含有量最多的气体是氮气； （2）最简单的有机物的是甲烷； （3）医用体温计里的液体How time flies! Three years have passed since I 小题1:(进入)the schoo1．As a Senior Three student，it won’t take long小题2:I graduate. High school is regarded as the golden time in aperson’s life．Now，I have much to share  小题3: my schoolmates．Firstly，I’d like to show my appreciation to those s 小题4: by me all the way，teachers，parents and 小题5:  (朋友)included. Without their help and advice，my life would be different. 小题6:   ，it's high time to say sorry to classmates whom I hurt or misunderstoods . 小题7: (交际)and smiles act as bridges to friendship．More importantly，I’ve made up my mind to make every  effort to  study，for  I  believe  hard work  is the key to success． Just as the old saying g 小题8:  ，“No pains，no gains．”Finally，I hope that every one of us can a 小题9:  his/her dream in the near future．I’ll attachgreat significance to our friendship formed at school，and I'd like to keep in contact with you after graduation．Meanwhile，I suggest all the younger fellows make f 小题10: use of time，because time waits for no one．