题干

若以鸡蛋蛋白液为材料进行蛋白质鉴定实验,发现蛋白液与双缩脲试剂发生反应后会粘固在试管壁上。下列关于这一现象形成原因的描述中正确的是

A:鸡蛋蛋白液稀释不够,搅拌不匀

B:只添加了双缩脲试剂A,未添加双缩脲试剂B

C:鸡蛋蛋白液不是合适的实验材料

D:蛋白液与双缩脲试剂的反应时间不够长

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A

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A Guide to the University

Food

The TWU Cafeteria is open 7am to 8pm.It servessnacks, drinks, ice cream bars and meals.You can paywith cash or your ID cards.You can addmeal money to your ID cards at the Front Desk.Even if you donot buy your food in the cafeteria, you can use the tables to eat your lunch,to have meetings and to study.

If you are on campus in the evening or late at night, you canbuy snacks, fast food, and drinks in the Lower Café located in the bottom levelof the Gouglas Centre.This area isoften used for entertainment such as concerts, games or TV watching.

Relaxation

The Globe, located in the bottom level of McMillan Hall, isavailable for relaxing, studying, cooking, and eating.Monthlyactivities are held here for all international students.Hours are 10am to 10 pm, closed on Sundays.

Health

Located on the top floor of Douglas Hall, the Wellness Centre iscommitted to physical, emotional and social health.A doctor andnurse is available if you have health questions or need immediate medical helpor personal advice.The cost ofthis is included in your medical insurance.Hours areMonday to Friday, 9am to noon and 1;00 to 4;30pm.

Academic Support

All students have access to the Writing Centre on the upperfloor of Douglas Hall.Here,qualified volunteers will work with you on written work, grammar, vocabulary,and other academic skills.You can signup for an appointment on the sign-up sheet outside the door two 30–minuteappointments per week maximum.This serviceis free.

Transportation

The TWU Express is a shuttle(班车) service.The shuttletransports students between campus and the shopping center, leaving from theMattson Centre.Operationhours are between 8am and 3pm.Saturdays only.Round tripfare is $1.