相当于All means（ that were possible） have been used to save him
因为All means所以要have ,were
All means that _____ possible _____ been used to save him
A.is; have B.were; have
C.was; has D.are; has
B.为什么?
相当于All means（ that were possible） have been used to save him
因为All means所以要have ,were