One particular doubt nagged.

But doubts nagged him.

A doubt nagged at her.

Still the doubts nagged at her.

But Abernathy's veiled warning and his own doubts nagged at him nevertheless, and he could not seem to set the matter to rest.

Her voice was calm, but inside, doubts nagged at her.

If doubt ever nagged him, he says, "all I had to do was look out the window of the bus and see bare-chested Black men picking in the cotton fields."

A small doubt had nagged in his mind ever since the affair in the transmitter room, when Modesty had been caught attempting to send out a message.

The doubts still nagged him, but he shrugged and said, "What have I got to lose?

Dan had always been skeptical of facile parlor psychoanalysis, but the doubts nagged at him when he was apart from Carrie.