同根常考词汇：需掌握
◆dioxide[dai’ksaid]n.二氧化物
举例：The lime water has turned cloudy，therefore carbon dioxide has been produced during the experiment.
石灰水变得混浊了，可见在实验中有二氧化碳生成了。
同形：oxide[‘ksaid]n.氧化物
◆dilemma[di’lem，dai‘lem]n.进退两难
举例：She was in a dilemma whether to stay at school or get a job.
是继续求学还是找工作，她感到难以决定。
