Before Mount Everest was discovered, what was the highest mountain in the world?

I know there are two methods by using three time the same number with a plus(+) operator , you can make sum as 60.

One of them is 20+20+20.

whats the other way ?

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

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

What breaks yet never falls, and what falls yet never breaks?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

Without looking at a calendar, within a minute name, a boy's name using 5 consecutive 1st letters of 5 consecutive months

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?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

If you say my name, I will no longer exist. What am I?