What work can one never finish?

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

1. What does:
TIM JOB
represent?

2. What does:
MO_ _
represent?

Once upon a time, there was a castle on a square island. The entire island was surrounded by a 14m wide trench. The Romans had wanted to invade the castle and had brought a few wooden planks along with them to facilitate themselves in crossing the moat. The planks were however found to be only 13m long.

The Romans still managed to cross the trench. How did they do it?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

I am white when I am dirty, and black when I am clean. What am I?

What is full of holes but still holds water?