题目

When should people be made to retire? 55? 65? Should there be a compulsory (强制的) age limit? Many old people work well into their 70s and 80s, running families, countries or corporations. Other people, however, despite being fit and highly talented, are forced to retire in their fifties or even earlier because of the regulations of a company or the nation. This essay will examine whether people should be allowed to continue working as long as they want or whether they should be encouraged to retire at a particular stage. Some people think there are several arguments for allowing ol13．一本书放在水平课桌上处于静止状态．下列各对力中，分析正确的是（　　）A．书对桌面的压力和桌面对书的支持力是一对平衡力B．书受到的重力和书对桌面的压力是一对相互作用的力C．课桌受到的重力和地面对课桌的支持力是一对平衡力D．书受到的重力和课桌对书的支持力是一对平衡力