题目

能保持二氧化碳化学性质的最小微粒是（   ）  A. 二氧化碳分子                        B.氧分子  C.碳原子                               D.氧原子 答案：A2、根据已给出的首字母，在短文空白处填入适当的单词，是其内容通顺。每空限填一词，将完整的单词写在短文后面的横线上。 You are doing homework and waiting for you parents to come back. The doorbell rings. You stand up and look t___1_ the keyhole. Two strangers! And the bell goes on ringing. Should you open the door at once? Instead if o__2_ the door immediately, you should ask who’s there with the door locked, If it’s a stranger, say, “Come back latter.” Don’t tell him or her that your parents are a_3__. Say Mum’s in the kitchen or Dad’s taking a shower, To ignore(忽视)the doorbell is not a good I__4__. Sometime thieves ring doorbell to see if anyone’s at home. In fact, there are many things that you should watch for when you  are alone at home. Keep the door I___5___ when you are alone. Keep a handy list of phone numbers to call for help-110，the p_6____ department, or a nearby friend. Never go anywhere with someone you don’t know, no matter h__7___ nice the person seems.