为什么说英语中的介词是学习的重点也是难点呢?因为同样一个名词或名词短语与不同的介词短语连用,意思会不一样,有的时候甚至相差甚远,如 at school 和 in school,in the road 和 on the road 等等。
那么在介词的实际应用中要如何把握使用介词的度呢,这其实还得从介词的实际用法出发才能深入了解具体的应用,如 on demand 和 in demand,它们到底要怎么区分呢?
On 的用法丰富多彩,作介词时,其中一个意思是“根据,由于”等,相当于 according to 或 because of,例如:
On their advice I applied for the job.
我听从他们的建议申请了这份工作。
He inherited a quarter of a million dollars on his mother's death.
由于他母亲去世,所以他继承了25万美元。
I have it on good authority that there's no way this light can cause skin cancer.那么 on demand 就是根据要求,可以意为“一经要求或按需”等,通常指任何使用都可以要求,例如:The pharmaceutical factory is manufacturing drugs on demand.They can give you a Home Delivery service of medicine on demand.由 on demand 衍生出来的 on-demand,相当于 available,例如:A number of networks are offering up free on-demand programming.There are many reality TV shows available to stream on-demand.They will sell a voice recognition product as an add-on, on-demand service for their users.他们将销售一种语音识别产品,作为用户的附加、按需服务。
二、in demand
In 的用法也丰富多彩,作介词时,其中一个用法是用来表状态或状况,例如:
The house is in good repair.I must put my affairs in order.那么 in demand 就是处于需求中,可以意为“需求大,很抢手”等,例如:Good secretaries are always in demand.Now that the property market has begun to boom, construction workers are in demand.Well-qualified young people with experience in marketing are very much in demand at the moment.在实际的应用中要彻底掌握每个介词的用法,只有这样才能更深入了解某些介词短语的构造以及它们所表达的意思。