watch 是行为动词,用在一般现在时肯定句中有两种结构,1.当主语是非第三人称单数时( I,we,they,you 等) 后跟动词原形,如:I often watch TV in the evening.
2.当主语是第三人称单数( she,he,Tom 等) ,动词用第三人称单数动词,如:My mother often watches TV in the evening.