Réponse :

Hello !

1) (-) The children were not happy.

(?) Were the children happy ?

2) Helen did eat an apple at lunch. or :  Helen ate an apple at lunch, both form are correct :)

Did Helen eat an apple at lunch ?

3) The babies did cry a lot yesterday. or : The babies cried a lost yesterday.

The babies didn't cry a lot yesterday.

Good Luck

Hello !

1. (-) The children weren't happy.

(?) Were the children happy ?

2. (+) Helen eat an apple at lunch.

(?) Didn't Helen eat an apple at lunch ?

3. (+) The babies cry a lot yesterday.

(-) The babies don't cry a lot yesterday.

Hope you understand !