[1] If you don’t have good nutrition(营养), you’re missing a key weapon against colds. Basics include vegetables and nuts .The following are five surprising foods that can improve immunity(免疫力).
[2] Yogurt. Yogurt, a milk product, contains probiotics(益生菌). These probiotics change the immune system and help reduce the severity of colds. Choose the yogurt that contains live and active probiotics to make sure you’re getting the benefits of the yogurt.
[3] Green tea. A cup of green tea can help cure a sore throat and lift spirits. Green tea can help prevent damage in the body. It may also fight against colds.
[4] Garlic(大蒜). Garlic has received widespread attention for its possibility of disease-prevention and immune-improving functions. In a study, researchers found that people who              regularly were two-thirds less likely to catch a cold. The best way to get garlic’s benefits is eating it without cooking. 
[5] Orange-fleshed (有橙色的果肉的) vegetables. Pumpkins, sweet potatoes, and other orange-fleshed vegetables are high in beta carotene (胡萝卜素)，which the body uses to make Vitamin A. A diet low in beta carotene can reduce immunity, so eating vegetables is a great way to ensure your body has the nutrients it needs. Vitamin A is also important in keeping skin healthy.
[6] Oysters(牡蛎). Oysters are definitely not the first thing that comes to mind when a cold or other illness attacks you, but they are a great source of zinc (Zn). Zinc is important in the development of white blood cells. It’s best to get zinc from a balanced diet. In a addition to oysters, beef and chicken are good sources.
What does the text mainly talk about? ( no more than 8 words)
                                                    
What kind of yogurt should people choose according to the second paragraph? ( no more than 8 words)
                                                   
List two benefits of green tea. (no more than 10 words)
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Fill in the blank in Paragraph 4 with proper words. ( no more than 4 words)
                                                 
What does the underlined word “it” in Paragraph 5 probably refer to? ( no more than 2 words)