Pro-sentences 

Here is a list of the most common pro-sentences in English:

The most basic forms of pro-sentence in English are the words, 'yes' and 'no' which express affirmation and denial of a sentence, respectively.
For example, 'yes/no questions' only require a 'yes' or a 'no' as the answer. However, the single word represents a larger sentence.

Certain adverbs can act as pro-sentences to answer questions. They are considered pro-sentences because they replace a whole sentence an eliminate the need to repeat it. The following types of adverbs can be used as pro-sentences:

Some discourse markers can act as a pro-sentence. Three of the most common ones are:

Now, take a look at some examples:

With some verbs, especially in short answers, we can use 'so' instead of repeating the whole sentence. For example:

Sometimes we use 'so' at the beginning of the sentence, especially in short responses with reporting verbs such as 'believe', 'say', 'tell', 'hear', and 'read':

We can use 'so' after verbs such as 'assume', 'believe', 'expect', 'guess', 'hope', 'imagine', 'presume', 'suppose', and 'think' instead of repeating the whole sentence, especially in short answers. For example:

"Not" can come before verbs of expectation and belief such as 'guess', 'hope', and 'suppose' to avoid repeating a sentence and express a negative meaning. For example:

We can use 'that' or 'this' to refer back to a whole clause, without repeating the actual words. For example: