图7为一提升装置运动简图。齿轮1为输入轮，蜗轮4为输出轮。蜗杆3’右旋。已知z₁=20，z₂=50，z_2’=15，z₃=30，z_3’=1，z₄=40，求传动比i₁₄。

Tom's mother demanded that she ________ everything on time.  [ ]

A. would tell    

B. tell        

C. have told      

D. be told