【正文】 氧核苷酸的排列順序不同 （4）61 mRNA （5）9000 1499 （6）1/934．（1）①3組②S型細(xì)菌中的某種物質(zhì)（轉(zhuǎn)化因子）能使R型細(xì)菌轉(zhuǎn)化成S型細(xì)菌，產(chǎn)生可遺傳的變異 （2）①第一步：從S型細(xì)菌中提取DNA，制備符合要求的培養(yǎng)基。結(jié)論：凝乳時(shí)間相等且最短的相鄰兩個或幾個溫度的平均值（或范圍）即是酶的最適溫度。(7)%。當(dāng).練習(xí)五一、 選擇題 二、 填空題9．；；10．；11．；12．；13．三、 解答題14．解： 因?yàn)椋瑒t所以拋物線在兩點(diǎn)處的切線方程分別為與 15 ．，由，得∴＋－＋∴的遞增區(qū)間為，及，遞減區(qū)間為當(dāng)時(shí)，有極大值，；當(dāng)時(shí)，有極小值，由上，故有在及上遞增，在遞減，由題設(shè)，恒成立，∴，或 英 語練習(xí)一一、詞匯辨析1) event 2) accident 3) incident 4) pain 5) hurt 6) ache 7) adventures 8) venture 9) venture 10)matter 11) business 12) thing 13) affairs二、單項(xiàng)填空15 C A D B A 6—10 C DB D D 11—15 D B D D D 16—20 A B D A B 21 25 B B A A B 26 30 C D B B B 三、完型填空15 A C B D B 610 A C D B D 1115 B A C C D 1620 A C D D A四、閱讀理解17 C A D C C C 812 C C B A C五、短文改錯 Children’s Day was ing. So Mum took Lily to go shopping. They first came to a cloth clothingshop. There were many different kinds of dresses on the shelves. Some were really beautiful.Mum asked Lily with a smile, “Which one did you like best?” Lily said, “I don’t want anyone do any oneof them!” Then they went to a bag shop. There were such many nice bags that people can’t so couldn’ttell which was the best. But Lily had no interest in them after all. So Mum took her to a atcandy shop. Mum knew that Lily liked sweets. But to her surprised, Lily gave the same surpriseanswer “NO”. Mum had no idea. At last, she took Lily to a toy shop. Many love toys were lovelydisplayed in the shop, like dogs, cats, bears and so on. Mum thought Lily may want to buy mightsome. So she asked Lily, “Well, what do you want?” Suddenly, a plane was flying overhead.Lily pointed to the plane and said excited, “I want that plane!” excitedly練習(xí)二一、詞匯辨析1) struggle 2) campaign 3) war 4) battle 5) fighting 6) cloth 7) clothing8) clothes 9) dresses 10) country 11) states 12) lands/countries 13) nations二、單項(xiàng)填空15 D C A A A 610 D D B D C 1115 C D B B D 1620 C BCCA 2125 A D B B A 2630 C C B D B三、完型填空15 A C B A D 610 D B C B A 1115 D B C D B 1620 A C D C A四、閱讀理解16 C B A B C D 710 D A C C五、短文改錯Alice is a beautiful and clever girl. One day beautiful night, she went out and laid on the 刪去 laygrass, looking into the sky with many, many stars were blinking. She was enjoying the 刪去shining stars and the cool fresh air while she saw a shooting star falling from the sky. Shewhen was very happily and excited. And she thought that she might also be a falling star long ago. Happy fallenShe thought and thought. After a while she felt asleep and made a nice dream. She dreamed fellthat she became a good friend of the rabbit star. And the rabbit star invite her to ride on him. a invited They had a fun flying freely in the huge and clean sky.刪去練習(xí)三一、詞匯辨析1) habit 2) customs 3) practice 4) strength 5) energy 6) power/ strength 7) force8) reason 9) causes 10) excuse 11) practices 12) training 13) exercise二、單項(xiàng)填空15 B C D C D 610 C B A A B 1115 C C D A A 1620 D D B B D 2125 A C C C C 2630 A B C C D三、完型填空1—5 A D B D B 6—10 D C C D A 11—15 D B C C C 16—20 B A D B B四、閱讀理解15 A B D C A 69 D C B D五、短文改錯This morning our teacher entered into the classroom with a smile on her face. She said 刪去her student, “Today is the last day you are at school.” All the kids were feeling a little sad, studentsbesides Xiaoxin. The teacher was moved to tears, and said, “I know you are unwilling