— Will you come to the net bars (网吧) with me? 　　　 

— Sorry. My mother always tells me ____ there.[ ]

A. not go　　　

B. go　 　

C. not to go　　　

D. to go

用一动滑轮将重1000N的物体匀速拉到高处，拉力至少为______N．