题目

第三部分：阅读理解（共20小题；每小题2分，满分40分） 请认真阅读下列短文，从短文后所给的A、B、C、D四个选项中，选出最佳选项，并在答题卡上将该项涂黑。 s5u.com A Your Genes, Your Future How would you feel if someone gave you an envelope with a description of every one of your genes? Supposing this information could tell you what illnesses you were likely to get, or even what illness you might die of, would you open the envelope? It's a difficult question to answer. But the fact is that scientists have already begun to discover how 在氢氧化钙的饱和溶液中，加入下列物质，不能使溶液的pH有明显改变的是 [　　] A．加入盐酸 B．加入石灰石 C．加入生石灰 D．通入二氧化碳