GIVE REASONS - WHY :
Some people use bi-focal lenses.

GIVE REASONS - WHY : Objects are not seen clearly when we enter from bright light to a room with dim light.

GIVE REASONS - WHY : The sun appears white at noon.

GIVE REASONS - WHY : We do not see the actual position of the stars.

GIVE REASONS - WHY : We have two eyes for vision instead of one eye.

GIVE REASONS - WHY : The colour of the clear sky is blue.

GIVE REASONS - WHY : The apparent position of the stars is not stationary.

GIVE REASONS - WHY : 'Danger' signal lights are red in colour.

Why are some transport proteins called pumps?