小刚同学做“弹簧的伸长与所受拉力的关系”的探究实验，记录数据如下：

由n（n≥2）个不同的数构成的数列a₁，a₂，…a_n中，若1≤i＜j≤n时，a_j＜a_i（即后面的项a_j小于前面项a_i），则称a_i与a_j构成一个逆序，一个有穷数列的全部逆序的总数称为该数列的逆序数．如对于数列3，2，1，由于在第一项3后面比3小的项有2个，在第二项2后面比2小的项有1个，在第三项1后面比1小的项没有，因此，数列3，2，1的逆序数为2+1+0=3；同理，等比数列 $1,-\frac{1}{2},\frac{1}{4},-\frac{1}{8}$ 的逆序数为4．

下列词语中划线字读音全部正确的一组是（    ）

在四边形ABCD中，，且·＝0，则四边形ABCD是         （     ）

阅读理解:阅读下列短文，然后从每题所给的四个选项(A、B、 C、和D)中，选出最佳选项。

    An important question about eating out is who pays for the meal. If a friend of yours asks you to have lunch with him, you may say something like this,“I'm afraid it'll have to be someplace cheap, because I have little money.” The other person may say, “OK, I'll meet you at McDonald's.”

    This means that the two agree to go Dutch, that is, each person pays for himself. He may also say, “Oh，no，I want to take you to lunch at Smith's,”or“I want you to try the Chinese dumplings there. They are great.”This means the person wants to pay for both of you. If you feel friendly towards the person, you can go with him and you needn't pay for the meal. You may just say, “Thank you. That would he very nice.”

    American custom(习惯) about who pays for dates (约会) are much the same as in other parts of the world. In the old days, American women wanted men to pay for all the meals. But, today, a university girl or a woman in business world will usually pay their way during the day. If a man asks her for a dance outside the working hours, it means “Come, as my guest.”So as you can see, it is a polite thing to make the question clear at the very beginning.