The best that the contact man could do was to post certain agents, in case they were needed.

He gave instructions that certain agents were to follow.

I made as if to rise, certain the agent would talk me into staying.

But some of them listen to certain agents, or others, and they believe they're better than they are.

Children who attend day care and their families are more likely to be exposed to certain infectious agents.

In a low whisper, he issued instructions to certain agents.

Usually, however, it was simply a place where he received messages from certain agents.

"I'm expecting to hear from certain agents of mine sometime quite soon now."

They must be shaken, in the manner of a certain British secret agent.

His instructions were for certain agents to cover that area again, by air.