The need to communicate is a key characteristic of human society.

　　需要交流是人類(lèi)社會(huì)最重要的`一個(gè)特征。

　　Cost was a key element in our decision.

　　價(jià)錢(qián)是我們決策時(shí)考慮的主要因素。

　　Good communication is key to our success.

　　良好的溝通是我們成功的關(guān)鍵。

　　These units played a key functional role in the military operation.

　　這些單位在軍事行動(dòng)中起到了主要的職能作用。

　　The president appears likely to change course on some key issues.

　　總統(tǒng)看起來(lái)可能要在某些重要問(wèn)題上改變方針。