B．By doing the study online.

　　C．By carrying out interviews.

　　D．By asking personal questions.

　　3．What can we learn from Paragraph 5?

　　A．Australian foods are healthier.

　　B．A healthy diet is actually cheaper.

　　C．Health foods are becoming more expensive.

　　D．People choose junk foods for their low prices.

　　解析：选B　推理判断题。根据第五段中的"a family of two adults and two children spends about 18% more on present diets than would be required to buy healthy diets"可知，研究结果表明，垃圾食品的花费已经超过健康食品，健康食品其实更便宜。

　　4．What might a following paragraph be about?

　　A．The harm of junk foods.

　　B．How we can eat healthily.

　　C．Why people choose junk foods.

　　D．The advantages of a healthy diet.

　　解析：选C　推理判断题。根据最后一段可知，作者认为，目前人们在垃圾食品的消费上已经超过了健康食品，这说明人们选择垃圾食品的原因不是价格，而是别的原因。由此判断接下来文章最有可能讨论人们选择垃圾食品的原因。

　　B

　　That most Americans are falling short of the recommended eight hours of sleep per night is nothing new.Over time, staying awake in the night can come with a high cost.You should stop your night owl (夜猫子) habit.

　　Compared with people who turn in early, those who go to bed very late are more likely to suffer from repeated negative thoughts.The findings suggest that sleep disruption (扰乱) could actually be linked to the development of negative thoughts.Psychologists suggest that focusing on good sleep habits can help.

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