你独自在家时有人敲门，来人自称是你家装修过的工人，有工具落在你家，要你开门取走工具，这时你应（ ）
A：给他开门
B：告诉他父母不在家，请他留下电话与爸爸联系
C：让他在门口等着
D：看着像好人就开门，不像好人就不开
设集合M={x|x2+2（1﹣a）x+3﹣a≤0，x∈R}，M⊆0，3，求实数a的取值范围．
Mrs Li is a teacher．However,she for a newspaper one year ago.
— It's not officially confirmed yet. The committee are _________ it over.
