Grammar Girl
The sentence --I went to the store and I bought fruit vegetables and meat -- needs this number of commas.
What is two?
These handy devices tell the reader that what comes next is directly related to what preceded it.
What is a colon?
In Jimmy Breslin's story about the man who dug the grave for JFK, he is "It's an honor" to illustrate this writing technique.
What is repetition?
Sentences beginning with these two words are using a different kind of sentence structure called an expletive construction. They should be avoided.
What is there is/there are?