Many students agreed to come, but some students against because they said they don''t have time.

A．did not because they say they did not

B．were against because they say they don't

C．did not because they said they did not

D．were against coming because they said they don't

关于引气剂的使用，说法正确的是( )。

A．引气剂和引气减水剂，用于抗冻、防渗、抗硫酸盐混凝土
B．宜用于蒸养混凝土和预应力混凝土
C．不宜用于泌水严重的混凝土、贫混凝土以及对饰面有要求的混凝土和轻骨料混凝土
D．混凝土中掺引气剂或引气减水剂，其掺量都较大