It is dark at night because there is no ______________.

Many objects, such as electrical appliances, computer and lifts use _______________________ to work.

We can see non -light sources because they __________ light.

Animals which live in water are known as _____________ animals.

The sun shines on the one half of _________.

A ___________ is an area of darkness.

Fish breathe with ___________.

An electric torch works on electricity from ______________.

_________ materials allow most light to pass through them.