请看一下这句话的翻译,我不懂后半句是怎么翻译出来的
It is obvious that the strength of a country's economy is directly bound up with the efficiency of its agriculture and industry ,and that this in turn rests upon the efforts of scientists and technologists of all kinds.
翻译答案:显而易见的是一个国家的经济实力与其工农业生产效率密切相关,而效率的提高则又有赖于各种科技人员的努力。
译文中的后半句让我很不解,“效率的提高”是从何而来呢?还有句中的"this in turn rests upon"是什么意思?我看它是与译文中“效率的提高”相对应的,为什么这样翻译呢?