Good Riddles

Question: My name can have any letter of the alphabet, but I always have 2 X's.

What am I?

Question: Take my first and make it my last, now I happened in the past.

What am I?

Question: Some use me, while others do not.
Some remember, while others have forgot.
For profit and gain I'm used expertly, I can't be picked off the ground or tossed in the sea.
Only gained through patience and time, can you unravel my rhyme?

Question: Two men play five sets of tennis together and each win three sets.

How is this possible?

Question: A semi truck is driving down the highway but the driver isn't paying attention. He goes under an overpass that is too short for his truck by only inches and gets stuck. He thinks it's going to be a very costly mistake but one of his friends happens to pass by and explains to him how he can get out in the matter of minutes without any help.

What does he suggest?