Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Can you decipher the below rebus?

PBLUESAISNUERSES

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?

A guy in his thirties is found dead in a forest. The shocking thing about the body is that he is wearing his swimming trunks snorkel and a facemask.

For your information, the nearest lake is some 10 miles away and the sea is hundreds of miles away.

How did he die then?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

Two natural numbers have a sum of less than 100 and are greater than one.

John knows the product of the numbers and Jacob knows the sum of numbers.

The following conversation takes place between them:
John: 'I am not aware of those numbers.'
Jacob: 'I knew you wouldn't be. I am not aware myself.'
John: 'Now I know them!'
Jacob: 'Now I know them, too!'

What are the two numbers?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

Different lights make me strange by changing me into different sizes. What am I?

What four weights can be used to balance from 1 to 30 pounds?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?