Can you replace the question mark with the correct number?

I go up and I go down.
I go up towards the beautiful sky and down toward the green ground.
I am present tense.
I am past tense too
Children love me.

Who Am I?

I know a nine-letter word having only one vowel.
Do you ?

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

How many runs at maximum can a batsman score in a normal one-day match? Consider the fact that the conditions are ideal and there are no No Balls, no Wide Balls and no Extras in that match.

A man was just doing his job when his suit was torn. Why did he die three minutes later?

If we tell you that there is a relation between the numbers and letters in the given figure, can you analyze it and find the missing letter in the last box?

What is the word or phrase?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?