What is in seasons, seconds, centuries and minutes but not in decades, years or days?

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

Can you name some countries which do not have the alphabet 'A' in them?

There are five men, let's say Tarun Harish Lavesh, Manoj, and Manish. All of them have a dot mark on their forehead. They can't see the dots on their forehead but can see the ones on others. The owner of WHITE Dot is an honest person and will never lie, while the owner of BLACK Dot always tells the lie.

This is the statement from Tarun Harish Lavesh and Manish:
Tarun: 'I see 3 whites and 1 black'
Harish: 'I see 4 black'
Lavesh: 'I see 3 black and 1 white'
Manish: 'I see 4 white'

What colour is the dot on each of Tarun Harish Lavesh, Manoj, and Manish's forehead?

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

Replace the question mark with the correct number in below Picture:

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?