英语周报2022-2022第15期九年级答案

5B【解析】格里菲思实验证明的是S型菌中存在转化因子能将R型菌转化为S型菌;艾弗里的实验思路是将组成S型菌的生物大分子分开研究其作用,故将S型菌的生物大分子分离提纯:噬菌体侵染细菌实验中,离心后细菌都主要处于沉淀物中;赫尔希和蔡斯的实验证明了DNA是遗传物质。故选B。

书面表达One possible version:Dear Mr. Smith.First of all, I would like to congratulate you on your school s sixtieth anniversary. The long history of theschool brings up its outstanding campus culture and educational concept. I take great pride in studying at thisexcellent school, At your invitation, I will perform a Chinese folk dance at the celebration ceremony to expressmy congratulations. Please prepare the audio equipment to play the accompanying music. I will prepare thedance music and costumes myself. I am delighted to be able to make a modest contribution to the promotion ofChinese culture and cultural exchanges between China and the UKBest wishes.Yours truly,Li Hu

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