1. ...often a part of something old that has remained when...

　　解析：remain既是不及物动词(意为“剩下；留下；遗留”)，也是系动词(意为“仍然；保持”)。作系动词时与stay的区别见本报第2期。

　　考例：Having a trip abroad is certainly good for the old couple, but it remains ________ whether they will enjoy it. (NMET 2002)

　　A. to see B. to be seen C. seeing D. seen

　　点拨：remain 当作“留待……；留下……以便……”意时为不及物动词，其后一般接不定式作宾语，故不选C、D；“那对老人是否喜欢到国外去旅游还要留待以后看”显然，应该是被看，故选B。有些同学误选D，可能只注意本题应用被动，却没有真正理解remain在本题中所表述意思的常见用法。

　　2. ...it easily melts when heated.

　　解析：在when, while, as, if, though, although, unless, once, until, whether, as if等连词引导的状语从句中，如果谓语有be的形式，并且其主语又跟主句的主语一致或是it时，则从句的主语和be常可省略。上句的完整形式为：...when it is heated.。

　　考例：

　　①The research is so designed that once _______ nothing can be done to change it. (NMET 2002)

　　A. begins B. having begun C. beginning D. begun

　　②Unless ________ to speak, you should remain silent at the conference. (上海，2003)

　　A. invited B. inviting C. being invited D. having invited

　　点拨：第①题根据句意其完整结构为...once the research is begun nothing...。A项是谓语动词， 选上后句子结构不对；而“研究开始付诸实施”显然应用被动，故不选表主动的B、C，而选D。第②题的完整形式为Unless you are invited to speak..., 本句的invite与主语you是被动关系，并且不是表达正在进行的动作，故选A。

　　3. ...a judge must decide which eyewitnesses to believe and which not to believe.

　　解析：疑问词+不定式一般在句子中作主语、宾语,表语等，且在这一结构中一般不用被动式和进行式。如：

　　Please tell me how to learn English well? 请告诉我如何学好英语？

　　考例：

　　I've worked with children before, so I know what _______ in my new job. (NMET 2000)

　　A. expected B. to expect C. to be expecting D. expects

　　点拨： 选B。what to expect 作know 的宾语。

　　4. ...which must be facts, rather than opinions.

　　解析：rather than意为“不是；不要；不愿”。如：

　　I'll have a cold drink rather than coffee. 我想喝冷饮，而不想喝咖啡。

　　常构成的短语是prefer to do A rather than do B，意为“宁愿做A而不愿做B”。

　　考例：

　　Rather than _______ on a crowded bus, he always prefers _______ bicycle.(NMET 1994)

　　A. ride; ride B. riding; ride C. ride; to ride D. to ride; riding

　　点拨：此题考察短语prefer to do rather than do 结构，当然也可以把rather than do置于句首，故选C。

　　(文/冯欣； 英语辅导报新课标高一版 04~05学年度第10期；版权归英语辅导报社所有，独家网络合作伙伴新浪教育，未经许可，不得以任何形式进行转载。)