What does does this rebus picture means ?

What brings you down but never up?

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

An exterior architect is asked by a builder to plant seven trees in a manner that there are exactly six rows of trees in a straight line and each row has three trees in particular.

How will he do it?

Consider this about a word: The first two letters signify a male, the first three letters signify a female, the first four letters signify a great, while the entire world signifies a great woman. What is the word?

I cannot talk, but I always reply when spoken to. What am I?

You are given with the following sum. Each of the letters can be decoded as a digit. If we tell you that D = 5, then can you solve it entirely?

DONALD
+GERALD
=ROBERT

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?