题目

二茂铁[(C5H5)2Fe] 分子是一种金属有机配合物，是燃料油的添加剂，用以提高燃烧的效率和去烟，可作为导弹和卫星的涂料等。它的结构如图所示，下列说法正确的是A．二茂铁中Fe2+与环戊二烯离子（C5H5-）之间为离子键B．1mol环戊二烯（）中含有σ键的数目为5NAC．分子中存在π键D．Fe2＋的电子排布式为1s22s22p63s23p63d44s2Taste is such a subjective matter that we don’t usually conduct preference tests for food. The most you can say about anyone’s preference is that it’s one person’s opinion. But because the two big cola companies—Coca-Cola and Pepsi Cola are marketed so aggressively, we’ve wondered how big a role taste preference actually plays in brand loyalty. We set up a taste test that challenged people who identified themselves as either Coca-Cola or Pepsi fans: Find your brand in a blind tasting. We invited staff volunteers who had a strong liking for either Coca-Cola Classic (传统型) or Pepsi, Diet (低糖的) Coke, or Diet Pepsi. These were people who thought they’d have no trouble telling their brand from the other brand. We eventually located 19 regular cola drinkers and 27 diet cola drinkers. Then we fed them four unidentified samples of cola one at a time, regular colas for the one group, diet versions for the other. We asked them to tell us whether each sample was Coke or Pepsi; then we analyzed the records statistically to compare the participants’ choices with what mere guess-work could have accomplished. Getting all four samples right was a tough test, but not too tough, we thought, for people who believed they could recognize their brand. In the end, only 7 out of 19 regular cola drinkers correctly identified their brand of choice in all four trials. The diet-cola drinkers did a little worse----only 7 of 27 identified all four samples correctly. While both groups did better than chance would predict, nearly half the participants in each group made the wrong choice two or more times. Two people got all four samples wrong. Overall, half the participants did about as well on the last round of tasting as on the first, so tiredness, or taste burnout, was not a factor. Our preference test results suggest that only a few Pepsi participants and Coke fans may really be able to tell their favorite brand by taste and price. 1.According to the passage the preference test was conducted in order to ________. A. show that a person’s opinion about taste is mere guess-work B. compare the ability of the participants in choosing their drinks C. find out the role taste preference plays in a person’s drinking D. reveal which cola is more to the liking of the drinkers 2. It is implied but not stated in the first paragraph that ________. A. the competition between the two colas is very strong B. blind tasting is necessary for identifying fans C. the purpose of taste tests is to promote the sale of colas D. the improvement of quality is the chief concern of the two cola companies 3.The word “burnout” (Line3, Para. 5) refers to the state of _________. A. being seriously burnt in the skin B. being badly damaged by fire C. being unable to function because of excessive use D. being unable to burn for lack of fuel 4.The author’s purpose in writing this passage is to ________. A. emphasize that taste and price are closely related to each other B. recommend that blind tasting be introduced in the quality control of colas C. show that taste preference is highly subjective D. argue that taste testing is an important marketing strategy