不能这样说,应该是说主语是第三人称单数的一般现在时时动词(除BE ,HAVE外）才要加S 或ES,句中的助动词/情态动词时,后面的动词要用原形,像你说的有do does must can在前面就不用加了,如
He likes playing basketball
He has lunch at home every day.
Does he have lunch at home every day?
He can swim.
问个低级的英语问题是不是第三人称单数时动词要加s啊?但是有do does must can在前面就不用加了,