正确表示基因操作“四步曲”的是[ ] A．提取目的基因一目的

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问题选择题

正确表示基因操作“四步曲”的是[ ]

A．提取目的基因一目的基因导入受体细胞一目的基因与运载体结合一目的基因的检测和鉴定

B．目的基因的检测和鉴定一提取目的基因一目的基因与运载体结合一目的基因导人受体细胞

C．提取目的基因一目的基因与运载体结合一将目的基因导入受体细胞一目的基因的检测和鉴定

D．目的基因与运载体结合一提取目的基因一将目的基因导入受体细胞一目的基因的检测和鉴定

答案

答案：C

完形填空

完形填空。
There are different kinds of trains in the world. Trains can 1 people, animals, and other things. Some trains are 2 , the others are slow. They can reach most of the cities and towns. Some trains go 3 the hills if they are too high to go over. In big cities, the streets are usually 4 and some cars and buses often have to wait. So you can find trains under the 5 and trains on a rail above the streets. People can quickly be brought in or taken out. Can a train run over 6 ? Yes, it can. There are many bridges over the rivers. But it is not easy to 7 bridges. Today's trains have dining-rooms for people. You may 8 something in them on the way if you are hungry. Trains are 9 to men, women and children. Many children like to play with model trains. With the model trains they can build their own rails and 10 thewonderful world of trains.
( )1. A. carry ( )2. A. help ( )3. A. through ( )4. A. full ( )5. A. seas ( )6. A. water ( )7. A. mend ( )8. A. cook ( )9. A. useful ( )10.A. hate	B. take B. expensive B. among B. dirty B. farm B. air B. watch B. eat B. polite B. are afraid of	C. bring C. fast C. during C. free C. ground C. forests C. reach C. find C. bad C. get on well with	D. hold D. empty D. above D. busy D. gardens D. mountains D. build D. pick D. lucky D. enjoy

单项选择题

男性，58岁。血压：162．6／109．9mmHg。经病史、常规体检及有关检查排除了继发性高血压。无心、脑、肾的并发症，无糖尿病、甲亢等合并症。服用美托洛尔1周后血压降至正常。但患者出现心动过缓、传导减慢等症状，这可能是美托洛尔阻断心脏哪种受体所致（）

A.α2受体

B.β2受体

C.α1受体

D.β1受体

E.M受体