Countable and Uncountable nouns - a, an, some

'A' and 'an' are used when we speak of a countable thing for the first time. 

Example:

A tiger was here just now.

The tiger was fierce.

'Some' is used with countable or uncountable nouns.

Example:

There are some salt.

There are some people in the room.

In this live workheet, choose whether to use 'a' , 'an' or 'some' in the sentences.