下列叙述中正确的有几项（   ）
①用聚乙二醇作诱导剂，能促使效应B细胞和骨髓瘤细胞融合
②植物组织培养过程中，需要用纤维素酶．果胶酶去除细胞壁
③进入血液的乳酸与碳酸钠反应所得到的乳酸钠在肝细胞内可进一步形成葡萄糖
④肺炎双球菌利用人体细胞的核糖体合成自身的蛋白质
⑤所有酶用双缩脲试剂进行检验都可以呈现紫色
⑥用氯化钙处理大肠杆菌，能增大其细胞膜的通透性

如图甲是连续分裂的细胞在不同时期DNA含量的测定结果，图乙是具有四条染色体的某细胞进行有丝分裂的简图，请据图回答：

无锡阳山地区有A、B两村盛产水蜜桃，现A村有水蜜桃200吨，B村有水蜜桃300吨．计划将这些水蜜桃运到C、D两个冷藏仓库，已知C仓库可储存240吨，D仓库可储存260吨；从A村运往C、D两处的费用分别为每吨20元和25元，从B村运往C，D两处的费用分别为每吨15元和18元．设从A村运往C仓库的水蜜桃重量为x吨，A、B两村运往两仓库的水蜜桃运输费用分别为y_A元和y_B元．

阅读下列短文，从每题所给的四个选项中（A、B、C和D），选出最佳选项，并在答题卡上将该项涂黑。

    Teachers at American colleges and universities have many different teaching methods. Some teachers give homework and check the work every day, and students in their classes have to take many exams. Some teachers give only writing tasks. Some teachers always follow a course outline and usually use the textbook, while others send students to the library for tasks.

    The atmosphere in some classrooms is very formal. Students call their teachers Professor Smith, Mrs. Jones and so on. Other classrooms have an informal atmosphere. Students and teachers discuss their ideas together. Teachers dress informally, and students call them by their first names. American teachers are different in their teaching styles.

At most American colleges and universities, libraries and learning centers can be used by students at any time. They can often use tape recorders, video machines and computers. They can buy books, notebooks and other things at campus stores. There are also services to students. They can get advice on their problems from their teachers. Colleges and universities usually offer facilities to students. Some schools have swimming pools and tennis courts. Most have fast food restaurants.

有效灌溉面积是指灌溉工程能够进行正常灌溉的水田和旱地面积之和。有效灌溉面积比例是指有效灌溉的耕地面积占耕地总面积的比重，它是反映农田水利建设的重要指标。下表为我国四个省区（海南、浙江、黑龙江、新疆）2013年的相关数据，据此完成下列各题。