266.exert……on……对……施加……
267.exert oneself to do sth.努力，使劲
268.come into existence (=begin to exist)开始存在;come into use开始使用;come into effect开始运转;come into fashion开始时新;come into action开始行动;come into power开始执政;come into sight进入视野;come into blossom开花;
269.(be) in existence存在come into existence出现
270.expect……of在……期望……
