—How much _______the shoes?

—________twenty yuan.[ ]

A. is; It is                

B. is; Is

C. are; It's                

D. are; They're

井巷中采用钢丝绳牵引带式输送机或钢丝绳芯带式输送机运送人员时，上行带下人平台的宽度不得小于（）m。