因此,对一个从事社会活动的人来讲,培养一种嗜好和新的情趣方式,乃是至关重要的对策。
The cultivation of a hobby and new forms of interest is therefore a policy of first importance to a public man.
将在适当的时候加以说明的,乃是这一数字的来源。
It is how this number is known that will be described in due course.
我遇到她乃是上上个礼拜。
It was the week before last that I met her.