单项选择题

The third paragraph is mainly about ______.

A．the harmful effects of chlorofluorocarbons on the environment
B．the necessity to ensure the environmental compatibility of new chemical substances
C．the economic feasibility of new chemical substances
D．the objective assessment of the progress in chemistry

<上一题目录下一题>

热门试题

单项选择题According to the passage, which of the following is a true statement, about sectional conflicts in America between 1763 and 1789

A．There conflicts were instigated by eastern interests against western settlers.
B．These conflicts were the most serious kind of conflict in America.
C．The conflicts eventually led to openly expressed class antagonism.
D．These conflicts contained an clement of class hostility.

单项选择题According to the passage, Loyalism during the American Revolutionary War served the function of ______.

A．eliminating the disputes that existed among those colonists who supported the rebel cause
B．drawing upper, as opposed to lower, socioeconomic classes away from the rebel cause
C．tolerating the kinds of socioeconomic discontent that were not allowed to exist on the rebel side
D．absorbing members of socioeconomic groups on the rebel side who felt themselves in contention with members of other socioeconomic groups

单项选择题The author considers the contentions made by the recent historians discussed in the passage to be ______.

A．potentially verifiable
B．partially justified
C．logically contradictory
D．ingenious but flawed

单项选择题University academics are concerned because ______.

A．young people are showing less interest in higher education
B．students cannot understand modem academic texts
C．academic books are too childish for their undergraduates
D．there has been a significant change in student literacy

单项选择题They youngest readers will quickly develop good reading skills if they ______.

A．learn to associate the words in a text with pictures
B．are exposed to modern teaching techniques
C．are encouraged to ignore pictures in the text
D．learn the art of telling stories