There’s no doubt about it,
drinking a coffee or any caffeinated drink
when you feel tired
will make you feel more alert
but let’s take a second
to think about what coffee is.
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doubt
I doubt the team will won the world prize.
They doubted the feasibility of the project.
The outcome of the election remains in doubt.
alert
She is alert to every sounds and movement.(adj)
The boy is alert in answering the police's questions.(adj)
The doctor alerted me to the danger of a heart attack.(v)
The supervisor was alerted me for weekend duty.