木瓜蛋白酶的水解片段包括()

A．两个Fab片段

B．一个F(ab')2片段

C．两个F(ab')2片段

D．多个Fc'片段

E．一个Fc片段

    Bruce _________his leg when he _____ in a football match yesterday afternoon.

A．broke; played

B．has broken; was playing

C．broke; was playing

D．was breaking; played