解题思路: 如下 解题过程: 若是一般现在时,有行为动词时用do,无行为动词时用be。 I am a student .(无行为动词,am表示“是"的意思) He is five years old .(无行为动词。 do 用于第一、二人称,第三人称复数 。若主语是第三人称单数形式,则需要用助动词does,如: e.g. Do you go to school by bike? (有行为动词go) Do we have lunch at school?(有行为动词have) Do they have lunch at school? Does he/she go to work in his/her car? 最终答案:略