阅读理解。 Do you know that it is your own immune system working against the virus that makes you uncomfortable when getting a cold, but not the virus itself? So when you have got a strong immune system and the virus is strong enough too, you will possibly get terrible cold symptoms (症状)? Vitamin C won't stop a cold It is claimed that Vitamin C helps by increasing white blood cells. However, many tests have shown that it does not prevent colds. At best, it only slightly reduces the rime of symptoms. Staying indoors won't protect you One of the most likely sources of cold viruses is your computer mouse or desk. A study of the cold virus in offices found that 47% of desktops, 46% of computer mice and 45% of telephones had cold viruses on them. Wrapping up warm won't protect you Colds are more common in autumn and winter. That's because the cool, wet and cold weather drives people indoors, where viruses may more easily jump from one person to another. And the distinct peak in colds (感冒高峰) is in September and early January, which is likely due to the return of students to schools and colleges after the summer and winter vacation. Old granny's chicken soup is right Granny's chicken soup is an old cure for colds since a long time ago. Scientists say it is true. Chicken soup does help cure a cold. Many canned soups are just efficient as homemade ones. 1. It is ________ that makes you uncomfortable when getting a cold. A. the virus itself B. Vitamin C C. the terrible cold symptom D. your own immune system 2. 'Staying indoors won't protect you' tells us that ________ indoors. A. there are many desks B. there are many telephones C. there are many cold viruses D. there are many computer mice 3. The distinct peak in colds is in September and early January. That's because ________. A. it's in autumn and winter B. the weather is cool, wet and cold C. students return to schools and colleges D. viruses can jump from one person to another more easily 4. Many canned soups are just efficient as homemade ones. The underlined word 'efficient' means ________ in Chinese. A. 有效的 B. 美味的 C. 值钱的 D. 方便的