单项选择题
A．at the end of the year B．in winter C．in summer D．whenever you wish
A．lying is an age-old human problem B．dishonesty increases as people get older C．people were dishonest in the 18th century D．it is social conditions that make people tell lies
A．a lot of the heat is reflected B．there are clouds and dust in the air C．different parts of the Earth receive and reflect different amount of heat D．different parts of the Earth have different sources of heat