friend and foe

基本解释

BACTERIA, like people, can be divided into friend and foe.
細菌和人一樣也有敵我之分。
Ozone is a chemical that can be both friend and foe to human beings — depending on where it is.
臭氧是一種利弊兩全的化學物質。是利是弊，這得看它在哪兒出現。
The lack of information on his condition led many, both friend and foe, to assume the worst.
由於缺乏關於他健康狀況的資訊，造成很多人士（無論敵友）都以爲發生了最壞狀況。

One of the most difficult things in life is to draw the line between friend and foe.
CENTERFORSECURITYPOLICY: Telling friend from foe
Excerpt: As friend and foe alike recognised at the end of January 1806, Pitt had bestridden a confusing and rapidly changing world with authority.
FORBES: Fact and Comment
Players can choose to build friendly relationships with other cities or form an intense rivalry through a dynamic and ever-evolving friend and foe system.
ENGADGET: EA opens SimCity Social on Facebook, really, really hopes you'll 'like' it