题目内容：
Passage 2Taste 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 or Pepsi, Diet 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
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