I have branches, but no fruit, trunk or leaves. What am I?

Can you replace the question mark with the correct number in the below table sequence?

What work can one never finish?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?

What has many keys but can’t open a single lock?

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?

What goes up but never comes down?

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

Find the next number in the series.
1 10 24 43 67 ?