问题补充：
---Why go to the supermarket with us ?
---Sorry , he is doing his homework now.
A. not let Tom
B. don’t let Tom
C. not let Tom to
D. not to let Tom
答案：
(答案→)A. not let Tom
B. don’t let Tom
C. not let Tom to
D. not to let Tom
解析：“let sb. do sth.”意为：“让某人做某事”
