There was a tall boy sitting in front of me, blocking my _____ completely.

At times, worrying is a normal________ to a difficult event or situation—a loved one being_______ in an accident, for example.

I didn’t know it could do terrible ______to your heart and lungs or ______was more difficult for smoking couples to become pregnant.

These companies succeeded because they were the first companies to make use of the ____________ of the internet and was thought highly of by some experts.

Beijing Man used fire for cooking food and also for light, warmth and ________ wild beasts.