题目

下列化学用语既能表示一种元素，又能表示一个原子，还能表示一种物质的是（   ）           A. O                                        B. N2                                        C. Zn                                        D. CO 答案：BTelephone services are developing ________ in big cities．A.more and more quicklyB.more quickly and more quicklyC.quicklier and quicklierD.quicker and quicker