Certain chemicals had to go against the back wall of the car, and others right up at the front.

Living things also need certain chemicals to maintain their health.

Giving drugs to fix the level of certain chemicals in the blood.

In turn, people will begin to do some serious thinking about storing or using certain chemicals.

It works by increasing the levels of certain chemicals in the brain.

Stay away from certain chemicals and other things in the environment that can increase your chances of getting cancer.

They work by helping to balance certain chemicals in your brain.

But it may prevent them by increasing levels of a certain chemical in the brain.

Experts believe that certain brain chemicals go out of balance to cause the disease.

So crying actually helps you to release certain chemicals from your body.