A:C22H44COOH
B:C21H33COOH
C:C21H31COOH
D:C22H33COOH
9____8=17
计算:﹣45×(19+113﹣0.4)
在登楼梯比赛中,小明同学从一楼匀速登上五楼,共用了12s,则他登楼时克服重力所做功的功率最接近于()