Which sentence correctly uses a colon? A healthy exercise routine includes tried and true injury-prevention activities: warming up, stretching, and drinking plenty of water. Like many new students, her first activities included: registering for classes, becoming familiar with the campus, and attending a special orientation. This month’s edition of the teen magazine features: profiles of influential artists, fashion trends, and social issues that many of today’s youth care about. Before leaving the house, he had to make sure he had: the directions to the event, an extra set of clothes, and a book to read while he waited.

A healthy exercise routine includes tried and true injury-prevention activities: warming up, stretching, and drinking plenty of water.

Explanation:  

The correct sentence uses a colon to introduce a series of activities that help a person avoid injury. The clause “A healthy exercise routine includes tried and true injury-prevention activities” is an independent clause because it can stand on its own. The information that follows lists the activities. Therefore, the use of the colon is correct.

Or for idiotic people

ⁱᵗ ⁱˢ ᵗʰᵉ ᶠᵘᶜᵏⁱⁿᵍ ʳⁱᵍʰᵗ ᵃⁿˢʷᵉʳ ʸᵒᵘ ᴾᴵᴱᶜᴱ ᵒᶠ ˢᴴᴵᵀ ˢˡᵘᵗ "ᴾᴱᴿᴵᴼᴰ" .

the answer is "the man who came here yesterday was selling magazines."

gerund phrase: writing a short story.

noun use: subject.