题目

TV news programmes report the weather．Radio stations tell US the weather too．Newspapers show us weather forecasts(预报)on maps． Why do people want to know about the weather? People want to make plans．Some people want to have a good time with friends．Other people want safety while doing their jobs． Airport managers need to know about the weather．In bad weather，their planes cannot fly．Farmers need to know about the weather．In bad weather，they must protect their crops．Fishermen need to know about the weather．In bad weather，they cannot go out to fish． Computers help 有理数a、b在数轴上的对应点如图所示，则下列各式中错误的是 [　　] A． ab＞0 B． a＋b＜0 C． ＜1 D． a－b＜0