完型填空

What is the best way to study? This is a very important question. Some Chinese students often1very hard for long hours. It is a2habit, but it is not a better way to study. An efficient(讲效率的) student must3enough sleep, enough food and enough rest. Every week you 4to go out for a walk or visit some friends or some nice places. It's good5your study. When you return to your studies, you'll find yourself6han before and you'll learn more.

Maybe we can7that learning English is8taking Chinese medicine. We don't mean that it's bitter (苦的). We mean that like Chinese medicine, the efficiency of your study9slowly but surely.10slowly but surely every day and effects will come just like Chinese medicine.

在中学时代，男女同学应“交往有度，纯化友谊”，这要做到：（   ）
①既要互相尊重，又要自重自爱　

②既要开放自己，又要掌握分寸
③既要主动热情，又要注意交往的方式、场合、时间和频率　

④禁止进行学习之外的交往

下面关于我国各民族分布的说法，正确的是（    ）

三个数的平均数是30，其中两个数是24和16，第三个数是____。