You can see it everyday, But cannot touch it at will. What is it?

Let's play a word game. Following are some meaningless words that can be completed by adding random letters on either side of the word.

For example, the word "rdo" can be formed into "pardon".

Using the same technique, can you complete the given words?
ecalc
airb
rinci
tibac
uidel
gorit
igna
eyho

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

What English word has three consecutive double letters?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

I taste better than I can smell. Who am I?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

What goes up but never comes down?

People put me on the table and cut me but do not eat me. What am I?