问题 选择题

如图是某静电场在x轴上的场强大小分布,已知场强方向垂直于x轴,则下列说法可能正确的是(  )

A.x轴上电势处处相等,且为零

B.在该电场中x1处的电势变化比x2处的电势变化快

C.原点O的电势最大

D.x1处的电势比x2处的电势高

答案

解;A、x轴上场强为零,但电势不一定为零,A错误;

B、由图象知x1处的场强变化比x2处的快,由公式U=Ed知x1处的电势变化比x2处的电势变化快,B正确;

C、场强大小与电势没有必然联系,故0点的电势不一定最大,C错误;

D、由B知x1处的电势变化比x2处的电势变化快,但不一定谁的电势高,D错误;

故选B

单项选择题
完形填空

Eating a diet high in processed food increases the risk of depression, research suggests. What's more, people who ate plenty of vegetables, fruit and fish actually had a lower risk of depression, the University College London team found.

Data on diet among 3,500 middle-aged civil servants were compared with their emotional state five years later, a British journal reported. They split the participants into two types of diet--those who ate a diet largely based on whole food,which includes lots of fruit, vegetables and fish,and those who ate a mainly processed food diet, such as sweetened desserts, fried food, processed meat,refined grains and high fat dairy products After accounting for factors such as gender, age, education, physical activity, smoking habits and chronic(慢性的) diseases, they found a significant difference in the future depression risk with the different diets.

Those who ate the most wholefood had a 26% lower risk of future depression than those who ate the least wholefood. By contrast, people with a diet high in processed food had a 58% higher risk of depression than those who ate a diet low in processed foods.

Study author Dr. Archana Singh Manoux pointed out there was a chance that the finding could be explained by lifestyle factor they had not accounted for. He also pointed in a paper that a Mediterranean diet was associated with a lower risk of depression, but the problem with that is if you live in Britain, the likelihood of you eating a Mediterranean diet is not very high.

Dr.Andrew McCulloeh, chief executive of the Mental Health Foundation, said, this study adds to an existing body of solid research that shows the strong links between what we eat and our mental health.

He added people's diets were becoming increasingly unhealthy. The UK population is consuming less nutritious, fresh produce and more saturated fats and sugars.

小题1:The text is mainly about         .

A.the increasingly unhealthy diet of the UK population

B.the link between processed food and depression

C.the relationship between physical and mental health

D.the emotional state of the British People小题2:What do we know about the participants?

A.They are of different ages from young to old.

B.They are from different walks of life.

C.They chose the diet they preferred.

D.Their state are also affected by other factors.小题3:What can we learn from what Dr. Archana Singh Manoux said?

A.It is difficult for most British people to have a Mediterranean diet.

B.The Mediterranean diet is the most healthy in the world.

C.Many studies have been done on the Mediterranean diet before.

D.The Mediterranean diet is not good for depression.小题4:Dr. Andrew McCulloch agrees that         .

A.our diets are closely related to our mental health

B.the present study needs more facts and other information

C.the UK population will become ill in the near future

D.more saturated fats and sugars should be taken in小题5:Why might the author have written this text?

A.To tell people what a healthy diet actually is.

B.To prove people’s diets are increasingly unhealthy.

C.To encourage people to cut down on processed food.

D.To introduce some experts on the research team.