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问题 单项选择题 A1/A2型题

质粒载体是在天然质粒的基础上为适应实验室操作而进行构建的，构建方法为（）。

A.人工构建

B.天然合成

C.化学提取

D.生物合成

E.以上都是

答案

参考答案：A

问答题

一火车以2m/s的初速度，0.5m/s2的加速度做匀加速直线运动，求：

（1）火车在第3s末的速度是多少？

（2）在前4s内的平均速度是多少？
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改错题

On January 5th, students in our school visited Robot World, which we saw a great diversity of robot. It was amazed to find those robots could do a great number of things just like real people, including playing chess, playing piano and drawing pictures. What’s more, the robots were in different kinds and shapes, which made us enjoyable. In addition, that excited me most was the show given by a group of robots. They danced just as if they are dancers on the stage. By visiting Robot World, I have learned a lot of about robots , especial about their functions and shapes. The great human wisdom is so powerful that it make us feel more comfortable live in the world.
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