— Her father is very rich.

— ______ She wouldn't accept his help even if it were offered. [ ]

A. What for?        

B. No wonder.    

C. No doubt.    

D. So what?

肌丝滑行时，与横桥结合的蛋白是（）

A．肌球蛋白

B．肌动蛋白

C．肌钙蛋白

D．原肌球蛋白