Incorrect: "The team are playing well."
Correct: "The team is playing well."
Incorrect: "The cats are eating it's food."
Correct: "The cats are eating their food."
Incorrect: "The medication had a positive affect on her mood."
Correct: "The medication had a positive effect on her mood."
Incorrect: "Their going to the park."
Correct: "They're going to the park."
Incorrect: "Walking down the street, the rain started to fall."
Correct: "Walking down the street, I felt the rain start to fall."
Incorrect: "I don't need no help."
Correct: "I don't need any help."
Incorrect: "I have less books than you."
Correct: "I have fewer books than you."
Incorrect: "He plays the piano good."
Correct: "He plays the piano well."
Incorrect: "Your coming with us?"
Correct: "You're coming with us?"
Incorrect: "Me and John are going to the store."
Correct: "John and I are going to the store."