用双背齿轮装置供给的的英文

double back geared

• 用:    40分钟跑完全程 run the c ...
• 双:    two; twin; both; d ...
• 背:    body's back
• 齿轮:    cogwheel; gear whe ...
• 装置:    installation; devi ...
• 供给:    supply; provide; f ...
• 的:    4次方是 The fourth po ...