1. But even in the most favourable circumstances
    即使是在最有利的环境中，

2. Given favourable conditions , this cherry tree will grow very rapidly.
    如果给它适宜的条件，这棵樱桃树会长得很快。

3. Under favourable conditions, a city with a billion inhabitants could be a very attractive and exciting place to inhabit.
    在顺利的情况下，一个拥有十亿人口的城市会成为令人非常愉快和向往的居住地。

4. In the first place, the time of learning the mother tongue is the most favourable of all, namely, the first years of life.
    首先，学习母语的时间是最有利的，也就是说，是在人生最初的几年里。