题目

There are two types of people in the world. Although they have equal degree of health and wealth and other comforts of life, one becomes happy and the other becomes unhappy. This arises from the different ways in which they consider things, persons, events and the resulting effects upon their minds. People who are to be happy fix their attention on the convenience of things: the pleasant parts of conversation, the well prepared dishes, the goodness of the wine and the fine weather. They enjoy all the cheerful things. Those who are to be unhappy think and speak only of the opposite thi地球同步卫星定点在赤道上空某一位置，对于这一现象，下列说法正确的是:A．同步卫星定点于赤道上空，是以太阳作为参照物的;B．同步卫星定点于赤道上空，是以地球作为参照物的;C．如果在同步卫星上观看地球，则地球在转动;D．如果在同步卫星上观看太阳，则太阳是静止的.