At the outset, it seemed necessary to be on guard against the other two.

一开始，似乎有必要提防另外两个。

youdao

In the absence of a common goal or common enemy, they prefer to be on guard against each other.

在缺乏共同目标或共同敌人的情况下，他们宁愿相互防备。

youdao

When you have to deal with the local merchants, you have to be on guard against being strung along.

你在和当地的商人打交道时，你必须提防上当受骗。

youdao

But she warned members of the public to be on their guard against the virus.

BBC: Flu rate 'at record low'

Governments spend vast sums on defence to guard against the remote chance that their countries may be invaded.

ECONOMIST: The case for pre-emptive action

Families should be on the lookout, and work with experienced legal and financial professionals, to help guard against financial exploitation.

FORBES: 4. Arturo Gatti