Regex Tuesday Challenge - Week Twelve

This weeks challenge is another slightly easier challenge. In it, you must fix the whitespace in a sentence or paragraph; before, there could be multiple spaces or tabs between two words. You must write a regex such that the final string has one space between words, and two spaces after full stops (hint; there will never be a tab following a full stop). New lines should be left alone.

To test a regular expression on the test cases below, type it into the text input. Each test case will be marked as passed or failed respectively - you are aiming to get as many test cases as you can to pass. Note that JavaScript must be enabled for this feature to work. The regex engine used is the JavaScript regex engine; it is similar to PCRE, but with a few differences.

Test cases (0/12)

This is already a valid sentence.
This is already a valid sentence.
Extra spaces
Extra spaces
Multiple extra spaces
Multiple extra spaces
Tab here
Tab here
Multiple tabs here
Multiple tabs here
Tab and spaces
Tab and spaces
Multiple tabs
Multiple tabs
Mixed whitespace
Mixed whitespace
Sentence. Sentence.
Sentence. Sentence.
Sentence with words. Sentence.
Sentence with words. Sentence.
The quick brown fox. Jumped.
The quick brown fox. Jumped.
There are 1.2 apples
There are 1.2 apples
Congratulations, your regex passes all the test cases! Remember to share this challenge.