What is the correct way to join two independent clauses?

Which of the following sentences uses a hyphen correctly?

What does the word “it’s” mean?

What is the difference between “affect” and “effect”?

Which of the following sentences uses correct subject-verb agreement?

What is the correct form of the word to complete the sentence: “She was the _______ person in the...

Which sentence is correctly punctuated?

What is a comma splice?

Which sentence uses an apostrophe correctly?

What is the correct way to write a sentence using direct speech?