Pick out the most effective pair of words from the given pair of words to make the sentences meaning fully complete.
Precautions while using Microwaves
Many materials such as glass, china, and most types of plastic can be used to cook food in a microwave. The microwaves easily pass through these materials. Thus, they are ideal to cook your food in. However, microwave energy gets reflected when utensils made of foil and metal are placed in it. Care has to be taken not to use such vessels in the microwave unless specifically recommended.