Questions 11 to 15 are based on the following passage.
Scratchy throats, stuffy noses and body aches all spell misery, but being able to tell if the cause is a cold or flu (流感) may make a difference in how long the misery lasts.
The American Lung Association (ALA) has issued new guidelines on combating colds and the flu, and one of the keys is being able to quickly tell the two apart. That’s because the prescription drugs available for the flu need to be taken soon after the illness sets in. As for colds, the sooner a person starts taking over-the-counter remedy, the sooner relief will come.
The common cold and the flu are both caused by viruses. More than 200 viruses can cause cold symptoms, while the flu is caused by three viruses—flu A, B and C. There is no cure for either illness, but the flu can be prevented by the flu vaccine (疫苗), which is, for most people, the best way to fight the flu, according to the ALA.
But if the flu does strike, quick action can help. Although the flu and common cold have many similarities, there are some obvious signs to look for.
Cold symptoms such as stuffy nose, runny nose and scratchy throat typically develop gradually, and adults and teens often do not get a fever. On the other hand, fever is one of the characteristic features of the flu for all ages. And in general, flu symptoms including fever and chills, sore throat and body aches come on suddenly and are more severe than cold symptoms.
The ALA notes that it may be particularly difficult to tell when infants and preschool age children have the flu. It advises parents to call the doctor if their small children have flu-like symptoms.
Both cold and flu symptoms can be eased with over-the-counter medications as well. However, children and teens with a cold or flu should not take aspirin for pain relief because of the risk of Reye syndrome (综合症)，a rare but serious condition of the liver and central nervous system.
There is, of course, no vaccine for the common cold. But frequent hand washing and avoiding close contact with people who have colds can reduce the likelihood of catching one.
According to the author, knowing the cause of the misery will help（）
A.shorten the duration of the illness
B.the patient buy medicine over the counter
C.the patient obtain cheaper prescription drugs
D.prevent people from catching colds and the flu
4CuSO4+2Fe2(SO4)3+2H2O。某工厂运用该原理生产铜和绿矾的工艺如下:
2Cu+2H2SO4+O2↑
Fe(OH)3+3H+。要求加入的试剂能与H+反应,不能引入除Cu2+、Fe3+外的其他杂质离子,不能与Fe3+反应,故供选试剂中只有B、E适合。(3)电解CuSO4溶液,其产物为Cu、O2和H2SO4。(4)Fe(OH)3与H2SO4反应生成Fe3+,最终要得到绿矾,故试剂a应为铁粉。(5)绿矾含有结晶水,从溶液中分离的操作步骤为蒸发浓缩、冷却结晶,最后过滤即可。(6)电解生成的H2SO4和O2也可循环