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问题 解答题

有的人有耳垂，有的人无耳垂．有耳垂受基因A控制，无耳垂受基因a控制．一对有耳垂的夫妇生了一个无耳垂的孩子．试问：父亲的基因组成为______，母亲的基因组成为______，这个孩子的基因组成为______．他们再次生育一个有耳垂的孩子的几率为______，生育一个无耳垂的孩子的几率为______．请写出其遗传图

______．

答案

一对有耳垂的夫妇生了一个无耳垂的孩子，说明夫妇双方的控制耳垂有无的基因组成都是Aa（否则，不会生出无耳垂的孩子），无耳垂孩子的基因组成是aa，如图所示：即这对夫妇再生一个孩子有耳垂的几率是75%，无耳垂的几率是25%．

故答案为：Aa；Aa；aa；75%；25%；

单项选择题

为了保证精密加工镗孔的不直度和圆度要求，坐标镗床应保证主轴前后轴承的预载过盈量，其中前轴承要求为（）。

A、0.003～0.006mm，

B、0.02～0.05mm，

C、0.002～0.003mm，

D、0.05～0.08mm。
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填空题


Dear Guests,
We would like to reduce the impacts this event has on the environment to a minimum (最小值), therefore we would like to encourage you to take part in our "Eco-Stay" program during your stay in this hotel.
To save water and reduce water pollution, we do not change the towels every day.
To reduce wastes of resource and energy, such single-use items as toothbrush, comb (梳子) and razor (剃须刀) will not be provided at the time of your check-in.
To reduce the impacts that waste has on the environment, we would like to encourage you to take part in our waste sorting and recycling program. Please place paper, glass and metal in the plastic bag in each room. The materials in the bag will be collected after the meeting, and be delivered to a waste collection station in the city where they will be further sorted and delivered to recycling facilities.
Eco-stay Guidance
The guidance intends to reduce the impacts on (46) .
The hotel will not change the towels every day in order to (47) .
(48) will not be provided in order to reduce wastes of resource and energy.
The purpose of the waste(49)program is to reduce the impact of the waste.
The materials will be delivered to a (50) .
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