What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

Which English verb becomes past tense just by rearranging the letters?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

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

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

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

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 man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

What runs around the whole yard without moving?

What can you catch but never throw?