有关城市及其服务范围的叙述，正确的是（ ）
A．相同级别的城市其服务范围肯定相同
B．城市在区域中居核心地位，必然位于其服务范围的几何中心
C．每个城市都有与之相应的服务范围
D．城市级别的高低与服务范围的大小呈负相关关系
答案：C
每个城市都有与之相应的服务范围，但一般级别越高，其服务范围越大，应呈正相关。同级别的城市因受各种因素的影响，其服务范围大小未必完全相同，其位置也未必在服务范围的几何中心。
We can’t live without food. Today our knowledge of food and what it does for our bodies is far more advanced than____1_____of the old times. Now we know____2___vitamins and how each kind of vitamins__3_____in the growth of a special part of our body._____4____ on the market all kinds of vitamins which we can take to______5____our lack of certain important things which are needed for good health.____6____ if we eat well and properly, the food that we eat will ___7____ our bodies and so there is no____8_____to take any kind of vitamins ____9____ our doctors tell us that our bodies are_____10____of something which can be supplied by it. Generally speaking, everything we eat ____11____ some good to our bodies, but if we eat ____12____ of one kind of food and pay______13____attention to others, we may have too much of one kind and not____14____ of others. Then we may be ____15___ trouble. We are often told___16_____ we must eat some meat every day in order to get the necessary proteins. That is only____17____true, for proteins are not found only in meat. We can also get them___18____some vegetables. The best advice about ____19___ to eat is that we should eat all kinds of food____20__ never too much of one kind.
|