题目

Late in April, a photo show was held in our school． It lasted a week and was a great success! All the photos were t______                            by the students themselves ．They were ______（大多数）color photos, but      some are black-and -white o_____, presenting our school life, the beauty          of nature, festival activities and so on．All the _____（作品）of art were               ______show in the reading-room on the second floor．Every day a large         ______ of students went to enjoy them, and they 从深海鱼油中提取的被称作“脑黄金”的DHA是一种不饱和程度很高的脂肪酸，它的分子中含6个碳碳双键，学名叫二十二碳六烯酸。它的分子组成应是　　 （　 ） A．C20H41COOH 　　 B．C21H31COOH　 C．C22H33COOH　 D．C21H33COOH