题目

阅读下列短文，从短文后各题所给的四个选项(A、B、C和D)中，选出可以填入空白处的最佳选项。 There was once a boy called Joseph Webb who always loved toshow off how many friends he had at school. One day his 1 said to him, “Joseph, I 2 you a big bag of popcorn that you don't haveas many friends as you think. I'm sure many of them are nothing more thancompanions.” Joseph 3 the bet at once. However, he wasn't sure howto 4 whether his schoolmates were real friends ornot, so he asked his grandfather. The old man answered, “Wait a minute.” Thenhe left and 5在细胞核中，储存遗传信息的载体是： A．蛋白质      B．DNA分子      C．染色体     D．线粒体