Mrs Marks bought a printer(打印机)yesterday．She was hbecause she could print anything she wanted at any time．H，after about an hour,she was angry because she couldn't print the colour blue．All the other cprinted fine，except blue，which was very unusual．

    She dto call the after-sales service department(售后服务部)to help her solve the problem．David answered the phone．He teverything he could think of to help Mrs Marks．He asked her to reinstall(重新安装)the programme，to reboot(重新启动)the computer and to turn the printer on and off. Nof these things helped．

    After hours of trying the problem swasn't solved．Finally,David asked Mrs Marks if he could go to her hand try to solve the problem in person．Mrs Marks agreed，and thim her address(地址)．When he arrived at her house,she showed him her computer and the printer．David uwhat the problem was right away.He told her，"From now on，print on white paper instead of blue!"