问题 选择题

多酚氧化酶是引起果蔬酶促褐变的主要酶类,其催化的最适温度为35℃、最适pH为5.7。下列各图表示在其他条件适宜并保持不变的情况下的有关变化,则

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A.图甲可以表示温度从100℃降低为35℃时,反应速率与反应物浓度的变化关系

B.图乙可以表示pH从5.7升高为7时,反应速率与反应物浓度的变化关系

C.图丙可以表示反应物浓度增加1/5时,生成物的量与时间的变化关系

D.图丁可以表示多酚氧化酶浓度降低1/5时,反应物的量与时间的变化关系

答案

答案:D

选择题
阅读理解

阅读理解。

     Important change took place in the lives of women in the 19th century. When men went out from

their farms to cities to seek jobs in industry, peasant women had to take over the sowing, growing, and

harvesting of the fields as well as caring for cattle and raising their children. When women also moved

to the cities in search of work, they found that it was increasingly. Separated by sex and that employment

opportunities for women were limited to the lower-paid jobs. Later in the century, women in industry

gathered mainly in cloth-making factories, though some worked in mining or took similarly difficult and tiring

jobs.

     In the 1800s, service work also absorbed (吸纳) a great number of women who arrived in the cities from

the country. Young women especially took jobs as servants in middle-class and upper-class homes; and as

more and more men were drawn into industry, homestic service (家庭服务) because increasingly a female

job. In the second half of the century, however, chances of other service work also opened up to women,

from sales jobs in shops to teaching and nursing. These jobs came to be done mainly by women and low paid.

     For thousands of years, when almost all work was done on the family farm or in the family firm

(家庭作坊),home and workplace had been the same, In these cases, women could do farm work or hand

work, and perform home duties such as child care and preparation of meals at the same time, Along with the

development of industry, the central workplace, however, such as the factory and the department store,

separated home from work, Faced with the necessity for women to choose between home and workplace,

Western society began to give particular attention to the role of women as homemakers with more energy

than ever before.

1. We learn from the first paragraph that _____ had been done chiefly by men before they went to

cities to seek jobs.

A. mining, teaching, and nursing

B. sewing clothes and mining

C. soeing, growing, and harvesting

D. caring for cattle and growing crops

2. Domestic service because a female job mainly because _____.

A. more and more women began to work in domestic service

B. women mainly worked as servants, nurses, and miners

C. service and industrial jobs absorbed more women than men

D. women enjoyed working as sellers, teachers, and miners

3. We know from the passage that in the 1800s _______.

A. more and more women began to work in domestic service

B. women mainly worked as servants,nurses,and miners

C. service and industrial jobs absorbed more women than men

D. women enjoyed working as sellers,teachers,and miners

4. This passage is about _____ in the 19th century.

A. service and industry

B. female and male jobs

C. women and their work

D. female jobs and the pay