Always. There are 10 millimeters in 1 centimeter.
The boy put toothpaste on the brush and put water on it. Next, he turned the sink down to seem like it is off. He used the water to scrub off the toothpaste so the brush was wet and had a little bit of new toothpaste. Then, he put breath mints in his mouth and waited 2 minutes and then came down.