How many lions are there in the zoo? There are 3 lions in the zoo.

How much gasoline is there left in the car? There is half a tank of gasoline left.

Is "there" required in these sentences? Why?


There stands in for abstract pronouns in these sentences. But in speech I will omit them...
"How many books are on the table?"
"How many books are there on the table?"
"How many books are on the table over there?"
which is/are legal grammatically? and which can only be used in speech?