“There was” and “there were” are the past form. Verb indicates if it is singular or plural. The negative form is “there wasn’t” and “there weren’t”. For question follows the same structure at the present. Was there a river? Where there many trees?

Infinitives are defined as to + base form of the verb. They have several functions. to + walk

1. Used as objects following certain verbs*. I wanted to tell you how much I appreciated your gift. He hesitated to ask the embarrassing question.

   
   
   
   2. Used as a shortened form of in order to. You must take this medicine (in order) to get well.
      

The verb base + -ing formed gerunds, for example: walk + ing = walking. If it functions as verb means the action is realizing. It may be a gerund or a present participle when a verb ends in -ing.

It is important to understand that they are not the same. When we use a verb in -ing form more like a verb or an adjective, it is usually a present participle:

• Anthony is fishing in the lake.
• I have a boring teacher in my Literature class.

In many kinds of English sentence, you will find the word "it" or the word "there" in the subject position. These are usually "impersonal" sentences -- sentences where there is no natural or direct subject. In this cases the subject is replaced by there or it that is why is called “impersonal it”. This introduction will help you to understand when to use "it" and when to use "there".