一指铅笔和一支钢笔的原价分别为a元和b元(b>a),若铅笔降价10%,而钢笔提价10%,则现在买一支铅笔和一支钢笔比原来多付( )元。
0.1b-0.1a
A: What shall I do I’ve got so many things on my mind now. Will anybody help me B: __________________
A. How can I get support from othersB. Don’t expect me to help you. Is there anybody who can help meC. Don’t ask me. It’s your baby, Mary. See, my hands are full.D. Sorry. I didn’t expect you are so busy.
各分类系统统一用以下的等级顺序,即依次为界、门、纲、目、()、属、种。
A.科
B.亚科
C.亚目
D.亚属