1、work on, work at
这两个短语动词都可以用作及物动词，均可表示“从事于，致力于”的意思，其后须跟名词，代词或者动名词作宾语，一般情况下可以互换,例如：They have been working on a design for a lighter plough.他们一直在设计一种比较轻的犁。They are working on a report of their investigation of synthetic rubber.他们在写一份合成橡胶的调查报告。He is working on a new novel.他正在写一本新的小说。They have worked on this subject for many years.他们研究这门学科已经有好多年了。She is working at some exercises.她在做练习题。They worked at it whenever regular field tasks are not pressing.日常的农活不紧迫时，他们就干这个。
work on除表示“从事于”的意思外，常见的意思还有“继续工作”。这时，on是副词，其后不能跟宾语。例如：They'll work on until sunset.他们将继续工作，直到日落。
2、worth, worthy to, worthy of, worthwhile
worth是“值得”的意思，一般看作介词（也有人认为是形容词），后面通常接（金额，时间，精力之类的）的名词或动名词。接动名词时，要用主动形式，表示的却是被动的意义。有时为了强调，worth前还可以用适当的副词修饰。例如：What is worth doing at all is worth doing well.凡是值得做的，就值得好好去做。This precision instrument is worth 10,000 yuan.这台精密仪器值一万元。The research work is worth our while.我们在这项研究工作上花了精力是值得的。 |
