But now it is realized that supplies of some of them are limited, and it is even possible to give a reasonable estimate of their “expectation of life”, the time it will take to exhaust all known sources and reserves of these materials.（84年考题）
分析：该句的骨干结构为“It is realized that …”，it为形式主语，that引导主语从句以及并列的it is even possible to …结构，其中，不定式作主语，the time …是“expectation of life”的同位语，进一步解释其含义，而time后面的句子是它的定语从句。五个谓语结构表达了四个层次的意义：A. 可是现在人们意识到；B. 其中有些矿物质的蕴藏量是有限的；C. 人们甚至还可以比较合理地估计出这些矿物质“可望存在多少年”；D. 将这些已知矿源和储量将消耗殆尽的时间。根据同位语从句的翻译方法，把第四层意义的表达作适当的调整, 整个句子就翻译为：
Television, it is often said, keeps one informed about current events, allow one to follow the latest developments in science and politics, and offers an endless series of programs which are both instructive and entertaining. (85年考题)
分析：在此长句中，有一个插入语“it is often said”，三个并列的谓语结构，还有一个定语从句，其中三个并列的谓语结构尽管在结构上属于同一个句子，但都有独立的意义，因此在翻译时，可以采用分句法，按照汉语的习惯把整个句子分解成几个独立的分句，翻译成：
Decision must be made very rapidly; physical endurance is tested as much as perception, because an enormous amount of time must be spent making certain that the key figures act on the basis of the same information and purpose.