何谓分离细胞的阳性选择法和阴性选择法?
参考答案:
凡根据细胞的特性和标志选择纯化所需细胞的方法叫阳性选择法;而选择性去除不要细胞,仅留下所需细胞的方法叫阴性选择法。
女子 * * 属:
A.血栓性浅静脉炎B.血栓性深静脉炎C.游走性浅静脉炎D.血栓闭塞性脉管炎E.动脉硬化闭塞症
情景选择。
1. 你这样介绍自己的妹妹:[ ]
A. This is my sister.
B. This is my new friend Lily.
2. 想知道有多少只鸟,你问:[ ]
A. How many books do you have?
B. How many birds can you see?
3. 向别人问你不认识的女人:[ ]
A. Who's that man?
B. Who's that woman?
4. 教师节向你老师说什么:[ ]
A. Happy Teacher's Day.
B. Happy Woman's Day.
5. 询问别人来自哪里应该说:[ ]
A. What are you from?
B. Where are you from?
6. 找不到你的钢笔,应该问:[ ]
A. Where's my pen?
B. Is this my pen?
7. 打扰别人时,应该说:[ ]
A. I'm sorry.
B. Excuse me.