Junk food is food that has a lot of calories but few nutrients (营养物质), vitamins and minerals (矿物质). Some food does have nutrients, for example pizza, but because it contains too many calories, it is 48______ called junk food. Fruit and vegetables are the best examples of good food. 49______ contain few calories and many vitamins and minerals. A healthy diet should include a variety of food, most of 50______ should be rich in nutrients. That does not mean that we are never allowed to eat junk food. 51______ of us who love French fries, sweets, ice cream and cheeseburgers can still enjoy an unhealthy bite every now and then. All we have to do 52______ to be careful how often and how much we eat 53______ it.

If we make the right choices about 54______ we eat, we will be healthier 55______ have more energy to enjoy the good things in life. A balanced diet combined with exercise is the key to a healthy life.

KTT8灾区救援电话连续工作时间是（）。

A.≥12h

B.≥24h

C.≥28h