What does this rebus mean?

O
N
C
E
TIME

Only one colour, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

I know a nine-letter word having only one vowel.
Do you ?

I am quite hot but become too cold if you remove the first two letters. What am I?

Why do Chinese men eat more rice than Japanese men do ?

You are a cab driver who pools passengers. You pick 3 people from a destination and drop 1 after an hour. 2 people climb aboard at the same time and you drop 3 at the next destination. After some time, you pick 2 passengers only to drop 1 after a short distance where 3 more passengers climb up the cab. You leave the rest of the passengers one by one to their destination and then come back home.

Can you tell the eye color of the cab driver?

I have teeth but i don't bite. Who Am I ?

How many times can you subtract the number two from the number fifty?

What is always in front of you but can’t be seen?

What Deficiency does the below rebus represent?

VIT_MIN