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（１）玉米和水稻很难利用常规杂交手段杂交的原因是 。
（２）获得PEPC基因后，将其导入土壤农杆菌的质粒中，以获得重组质粒，需要的工具酶
是 和 。
（３）玉米PEPC基因在水稻细胞中成功表达的标志是 ，该过程包括 和 两个阶段。
（４）该技术定向改变了水稻的性状，这在可遗传变异的来源中属于___ _____。 查看习题详情和答案>>
【小题1】 Betty is a good friend of m________. We often help each other.
【小题2】They have invited a_________(science) to give them a speech on space.
【小题3】Mrs. Chan told us to write as_________(care) as we could.
【小题4】 We Chinese sometimes__________(借) words from English when talking.
【小题5】Victor__________(敲) the door before he walked into the room. 查看习题详情和答案>>
根据下列句子的意思及所给的汉语提示，写出空缺处单词、固定短语或固定搭配的正确形式。
1.Basketball (发明) by a Canadian doctor, Jatnes Naismith.?
2.Some students (抱怨) that they have too much homework.?
3.What made you so (生气)??
4. Look! The sick man is very tired, but he is still _(练习走) without any help.
5. By the time I arrived there, the film had (开始)for about five minutes. 查看习题详情和答案>>
词语运用 （共5小题，每小题1分，计5分）
根据下列句子的意思及所给的首字母、英语或汉语提示，写出空缺处单词或固定搭配的正确形式。
1. We have English class every day except _________________(星期四).
2. It’s not ________(surprise) that many tourists come to visit Shanghai every year.
3. Chocolate is usually __________________ (children )favorite food.
4. –How long may I _________ (借)the new book? --Two weeks.
5. Jane began _______________(下象棋) when she was seven years old.
根据句意及所给提示，补全单词或用单词、固定短语、固定搭配的正确形式填空。
1.You don’t like running. I don’t like running, e_________.
2.Tomorrow will be my ____________ (十三) birthday.
3.Don’t ____________ (touch) it. It’s dangerous!
4.My father has ______________ (写) five books these years.
5.I want to have a talk with you _____________________ (面对面地).
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