We did our work.

(a)  

My brother is buying a car.

(a)  

I don't know the answer.

(a)  

I am eating a sandwich.

(a)  

Mary didn't bring food.

(a)  

I will write my name on the board.

(a)  

Luis isn't riding a bike.

(a)  

I saw an animal outside.

(a)  

Your mom doesn't speak English.

(a)  

I am not cutting the grass.

(a)  

Danny and Mike won't be leaving early.

(a)