Must I wash the dishes?否定回答：No,you need't.對(duì)
Can I...Yes,you can.No,you can't
Should I．．．?　　　　Yes,　　you　　should．　　No,　　you　　shouldn＇t．
1.He does not need_to　　do_______(do) too much homework.　　　　因?yàn)榍懊嬗弥鷦?dòng)詞does了,所以這里need是實(shí)義動(dòng)詞,要用to　 do
2.You need to eat more vegetbables.(改為否定句）　
You　 don＇t　 need　 to　 eat　 more　 vegetables．　
因?yàn)閚eed　后面沒有用動(dòng)詞原形,而加了to　 do,所以這里是實(shí)義動(dòng)詞