问题 不定项选择

土壤的酸性太强会带来害虫和疾病,阻碍植物生长,并析出有毒金属。目前,造成我国土壤酸化的主要原因是()。

A.空气中CO2浓度增大

B.滥施化肥

C.酸雨

D.大面积种植单一作物,生物多样性遭到破坏

答案

参考答案:B, C

解析:

空气中二氧化碳浓度增大会形成温室效应,造成全球气温上升,二氧化碳溶于水生成碳酸(弱酸性),但二氧化碳溶于水达到饱和的pH在5.6左右,不能算酸雨,且碳酸不稳定,容易分解,排除A项。氮肥施用过量是导致农田土壤酸化的主要原因,B项正确。当酸雨输入超过土壤缓冲能力时,土壤就会呈现酸化,使土壤的物理化学性质发生变化,C项正确。生物多样性遭破坏并不会造成土壤酸化,D项错误。

完形填空
Mental health is about the way you think and feel and your ability to deal with ups and downs. Even though you are mentally healthy, it doesn’t     1    that you don’t have a mental health problem.
Mental health is everyone’s business. We all have times when we feel down or     2   . Most of the time those feelings pass,    3    sometimes they develop into a more serious problem. It seems that our mental health doesn’t always stay the same. It can change as the environment changes and as you move     4   different stages(阶段) of your life.
Here are four practical     5    to look after your mental health. Making simple changes to how you live doesn’t cost much or take up lots of time. Anyone can     6  them.
●Talk about your feelings. It can help you stay in good mental health. It isn’t a sign of      7   , but part of your ability to do what you can to stay healthy.
●Eat well. What you eat and how you feel are     8    connected. A proper diet can have a good effect on your mental health.
●Keep in touch. Friends and family members can offer     9    suggestions which may help you keep active and solve practical problems.
●Take a break. It could be a weekend     10   new places to enjoy the nature, or even a ten-minute break from doing your homework. A few minutes can be enough to relax you.
小题1:
A.agreeB.meanC.doubtD.notice
小题2:
A.excitedB.satisfiedC.surprisedD.stressed
小题3:
A.butB.andC.soD.as
小题4:
A.awayB.insideC.through D.against
小题5:
A.answersB.repliesC.waysD.chances
小题6:
A.followB.findC.adviseD.count
小题7:
A.weaknessB.lazinessC.happinessD.richness
小题8:
A.easilyB.closelyC.equallyD.hardly
小题9:
A.difficultB.terribleC.strangeD.various
小题10:
A.protectingB.exploringC.providingD.imagining
单项选择题