I can cook the meals.（对）
.Sarah can cook the meals（对）
She can cooks the meals(错）
She cooks the meals.对
Sarah cooks the meals.对
注意,主语是三人称单数,句子是一般现在时,谓语才是三人称单数
过去时：I /She/ He/Sarah cooked the meals.没有区别
将来时：I /She/ He/Sarah will cook the meals 也没有区别
并且情态动词;must can shall should would may might could 后面都加动词原形小学五，六年级还没有学过去时，将来时 并且情态动词吧 晕 我都弄不懂哦，不好意思，不晓得你是小学五六年级的。那你记住是一般现在时，三人称单数，谓语就是用三单can就是个情态动词I/you/they /boys cookthe mealsShe/He/LIly/Mom /Sarah(三人称单数） cooksthe meals