问题 问答题

久置不用的深井、久未开启的菜窖底部都存在着二氧化碳,由于它不能供给呼吸,人如果长期呆在二氧化碳含量较高的环境中会窒息而死,因此,人们在进入这些地方之前会进行灯火实验,原因是______.

答案

因为二氧化碳不燃烧也不支持燃烧,用灯火实验进行验证时,可看出被检测地方二氧化碳含量的高低.

故答案为:如果灯火熄灭或燃烧不旺,说明了二氧化碳含量较高

阅读理解

Fish contains lost of omega-3 fatty acids.These fatty acids have been shown to help prevent heart disease,lower blood pressure and reduce the risk of strokes.Researchers suggest that these benefits of eating fish far outweigh the risks of getting sick from contaminated fish.

Ongoing studies find that omega-3 fatty acids work magic on the brain too.Pregnant? Go out and eat fish! One study tracked a group of expectant women who ate more than 340 grams of fish per week.It turns out they gave birth to children who,years later,scored really high on IQ tests.

How can you add fish to your diet? One way to begin is by replacing meat with fish in one meal a week.Instead of frying,which retains more fat,try boiling your fish in an oven or grilling it outdoors.And don’t be afraid to spice up your fish.Garlic,herbs other spices can add wonderful flavors to fish.

For lighter meals,keep a few cans of tuna or other fish on hand at all times.They’re great for making tasty sandwiches or fish burgers.If you get hungry in the middle of the morning or afternoon,try tuna on crackers.It’s hard to find a better snack.And parents,be sure to introduce fish to your children.It’s important for them to get used to eating it at a young age·

67.What does the writer discuss in this passage?

A.Chemicals in popular drinks                        B.The best way to lose weight

C.Famous fast food restaurants                        D.Reasons for having seafood

68.What does the writer point out about the women in the study group?

A.They cooked for their husbands.            B.They were going to have babies.

C.They grew their own vegetables.               D.They lived with elderly parents.

69.What does the author imply about omega-3 fatty acids?

A.They can make kids smarter.                           B.They are found in most foods.

C.They last for just a few days.                           D.They create significant risks.

70.Why is grilling better than frying?

A.It’s fancier.         B.It’s quicker.         C.It’s cheaper.         D.It’s healthier.

71.According to the author,when is a good time to have tuna on crackers?

A.At lunchtime.                                                B.During a party.

C.Between meals.                                       D.After midnight.

单项选择题 A1型题