cook a meal和cook the meal 都可以表示做饭，意思稍有不同
cook a meal 泛指 意思是 做一顿饭.
cook the meal the 表示特指，是已经有了特定的在讨论的.
例句
Not only did I cook the meal， but also I cleaned the floor.
我不但做了饭， 而且还把地板弄干净了.
Cook a meal together that you will both enjoy. Don't forget the dessert!
一起煮一道两人都喜欢的大餐。不要忘记甜品！
