Правильные предложения:

She is cooking dinner in the kitchen.The cat chased the mouse down the street.They have finished their homework already.The children were playing in the park all afternoon.The teacher will be grading the tests tomorrow.

Неправильные предложения:

He go to the store to buy some milk.She have went to the cinema last night.They is playing football in the yard.The dog is barked loudly at the stranger.We are eat dinner at 7 o'clock.