1、vital

必要的;至關重要的;必不可少的

The port is vital to supply relief to millions of drought victims.

這個港口對向數百萬旱災災民提供救援物資是至關重要的。

Nick Wileman is a school caretaker so it is vital that he gets on well with young people.

尼克·威爾曼是學校的管理員，因此與年輕人搞好關系很重要。

充滿活力的;生氣勃勃的

They are both very vital people and a good match.

他倆都很有活力，十分般配。

They have something important to say and vital and radical ways of saying it.

他們有些重要的事情要說，言辭會比較激烈。

2、constant

持續不斷的;重復的;一直存在的

She suggests that women are under constant pressure to be abnormally thin.

她暗示說女性總是處在保持身材異常瘦削的壓力之下。

Inflation is a constant threat.

通貨膨脹始終是個威脅。

恒定物;常數；常量；常項

In the world of fashion it sometimes seems that the only constant is ceaseless change.

在時裝界，有時似乎唯一永恒不變的東西就是不斷的變化。

Two significant constants have been found in a number of research studies.

若干研究已經發現了兩個重要常量。

恒定的;不變的

The average speed of the winds remained constant.

平均風速保持穩定。