阅读理解 Passage One Questions 46 to 50 are based on the following passage. "Sugar, alcohol and tobacco," economist Adam Smith once wrote," are commodities which arenowhere necessaries of life, which have become objects of almost universal consumption, and whichare, therefore, extremely popular subjects of taxation. " Two and a haft centuries on, most countries impose some sort of tax on alcohol and tobacco. Withsurging obesity levels putting increasing strain on public health systems, governments around the worldhave begun to toy with the idea of taxing sugar as well. Whether such taxes work is a matter of debate. A preliminary review of Mexico's taxation found afall in purchases of taxed drinks as well as a rise in sales of untaxed and healthier drinks. By contrast,a Danish tax on foods high in fats was abandoned a year after its introduction, amid claims thatconsumers were avoiding it by crossing the border to Germany to satisfy their desire for cheaper, fattierfare. The food industry has, in general, been firmly opposed to such direct government action.Nonetheless, the renewed focus on waistlines means that industry groups are under pressure todemonstrate their products are healthy as well as tasty. Over the past three decades, the industry has made some efforts to improve the quality of itsofferings. For example, some drink manufacturers have cut the amount of sugar in their beverages. Many of the reductions over the past 30 years have been achieved either by reducing the amount ofsugar, salt or fat in a product, or by finding an alternative ingredient. More recently, however, somecompanies have been investing money in a more ambitious undertaking: learning how to adjust thefundamental make-up of the food they sell. For example, having salt on the outside, but none on theinside, reduces the salt content without changing the taste. While reformulating recipes ( 配方) is one way to improve public health, it should be part of amulti-sided approach. The key is to remember that there is not just one solution. To deal with obesity,a mixture of approaches--including reformulation, taxation and adjusting portion sizes--will beneeded. There is no silver bullet.

单选题 What did Adam Smith say about sugar, alcohol and .tobacco?

单选题 Why have many countries started to consider taxing sugar?

单选题 What do we learn about Danish taxation on fat-rich foods?

单选题 What is the more recent effort by food companies to make foods and drinks both healthy and tasty?

单选题 What does the author mean by saying, at the end of the passage, "There is no silver bullet" ( Line 4, Para.7)?