[单项选择]Playing a major role in the economic life of the United States, （）.
A. women currently make up 46 percent of the work force
B. currently women make up 46 percent of the work force
C. the work force is currently made up of 46 percent women
D. 46 percent of the work force is currently made up of women

[单项选择]

Sleep plays a major role in preparing the body for an alert and productive tomorrow. But sleep is not a period of inactivity. The sleeping brain is highly active at various times during the night, performing numerous "house keeping tasks". These keep us alive and aid our ability to think and remember. Sleep also energizes the body and brain. Most people spend one-third of their lives sleeping and this will affect the other two-thirds in terms of alertness, energy, moods, body weight, perception, memory, thinking, reaction time, productivity and performance.
To limit sleep means our health and daytime potential are significantly reduced. So, good sleep strategies are essential in order to feel energized day after day. There is no strategy which works for everyone, so each person needs to experiment. One important thing is that you shouldn’t worry too much if you go a few nights without a lot of sleep. It won’t ruin your life. On any given night, one i
A. it is a period of complete inactivity for the brain
B. it helps us understand what we have already achieved
C. it makes us more effective when we are awake
D. it helps us to lose weight

[简答题]Excessive speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation.

[单项选择]Major life changes may play a role in as many as a quarter of chronic daily headache cases that arise among otherwise healthy adult men and women, study findings suggest. "Major life events may precipitate or co-occur with the development of chronic daily headaches," Dr. Ann I. Scher said. Major life changes literally shake up our world, and invite or pressure us to interact with life in new ways. To grow, we need to change our belief systems to allow for new levels of thinking and performance.
Scher, of Uniformed Services University, in Bethesda, Maryland, and colleagues assessed re ports of major life changes among 206 men and women who met criteria for chronic daily headache (180 or more headache days per year). They assessed similar reports from 507 men and women with "episodic" headache (2 to 104 headache days per year).
The investigators assessed changes in work, marital status, children’s status, or residence; as well as deaths of family or close friends. They a
A. To cause something to happen.
B. To prevent something from happening.
C. To predict something to happen.
D. To prepare for something to happen.

[填空题]______play a major role in the development of cancer.

[填空题]Price is a major{{U}} {{/U}}(considerate) for people in buying anything.