My father often asks me to (eat more vegetable){对划线部分提问}

What does your father often ask you to do?
再问： Why？
再答： (1) 因为原句为一般现在时态，第三人称单数，所以，用助动词does； (2) 因为划线部分为宾语补足语——动词不定式做宾语补足语，因此，用what to do形式。