Leaders from different parts of the world took part

in the discussion   the international treaty.

A．which leads to

B．leading to

C．led to

D．led to have

相须、相使配伍可产生的作用是（）

A.协同作用，增进疗效

B.拮抗作用，降低疗效

C.减毒作用

D.毒副作用

E.增毒作用