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问题 单项选择题

原核生物辨认转录起始点的是（）

A.σ亚基

B.β亚基

C.β′亚基

D.σ亚基

E.α2ββ′

答案

参考答案：D

解析：转录开始首先由σ因子辨认启动子形成转录起始复合物，加入几个核苷酸后σ因子从全酶上脱落。

单项选择题

患者男性，49岁。食管癌术后2小时，胸腔闭式引流鲜血达150ml/h，病人烦躁，BP 90/60mmHg(12/8kPa)，P92次/分，提示

A．应激性溃疡出血
B．吻合口出血
C．食道胃底静脉曲张破裂出血
D．吻合口破裂
E．吻合口梗阻
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单项选择题

Sometimes we have specific problems with our mother; sometimes, life with her can just be hard work. If there are difficulties in your (1) , it’s best to deal with them, (2) remember that any (3) should be done (4) person or by letter. The telephone is not a good (5) because it is too easy (6) either side to (7) the conversation.

Explain to her (8) you find difficult in your relationship and then (9) some new arrangements that you think would establish a (10) balance between you. Sometimes we hold (11) from establishing such boundaries because we are afraid that doing (12) implies we are (13) her. We need to remember that being (14) from our mother does not (15) mean that we no longer love her. If the conflict is (16) and you cannot find a way to (17) it, you might decide to give up your relationship with your mother for a while. Some of my patients had (18) "trial separations". The (19) allowed things to simmer down, enabling (20) .

（6）（）

A.on

B.for

C.off

D.to
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