What goes up but never comes down?

Name the three-letter word that can complete the below words:

A) L O _ _ _ E
B) E D U _ _ _ E
C) _ _ _ E R
D) _ _ _ T L E

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

_ _ _ IE _ _
_ _ _ IE _
_ _ IE _ _
_ _ IE _
_ _ _ _ IE

Like you see, some letters have gone missing from these words that contain the IE pair at some or the other place. The letters that will be used to fill the blanks are given below. Use them and form meaningful words. Can you do that?

A, C, D, F, H, K, L, M, N, N, O, R, R, S, S, S, T, T, Y and Y.

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

What will you call your mother's brother's brother-in-law?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?