题目

下列各组分子中属于含极性键的非极性分子的是（    ）A.CO2、H2S                                    B.C2H4、CH4C.Cl2、C2H2                                    D.NH3、HCl 答案：解析：此题考查键的极性和分子的极性。A中的CO2结构为O=C=O，H2S为，所以都含极性键，但H2S是极性分子；B中C2H4为  ，CH4为都含极性键，且都属于非极性分子；C中Cl2不含极性键，D中NH3、HCl为极性分子，都不符合题意。 答案：BIf you want to improve your English 1. (rapid), you’d better listen to BBC English 2. is part of the BBC World Service. It broadcasts all kinds of programmes, such 3. difficult grammar 4. (point), life in Britain, differences between written and 5. (speak) English and so on. So far BBC English 6. (become) a popular learning course. If you want to know some information about the programmes, you just need to write to BBC English 7. (ask) for it. 8. , 9. is easy for you to find out the information and follow the programmes. In China there are English programmes like Follow Me on the radio. They are usually easy to receive and understand and they are very 10. (use) to you.