What is full of holes but still holds water?

what does the below rebus mean?

What can you serve, but never eat?

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

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

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

You board a train. The train will have to enter a tunnel soon. You are claustrophobic. Which place is the best for you to sit?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

By moving exactly three matchsticks can you make the below equation true.It can be solved by 3 ways.

John can place six large boxes or nine small boxes into a carton.

Can you find out in how many cartons can he place sixty-six boxes in total?

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?