He walked directly towards her, and spoke to her in a low voice to avoid _____ by others.

A．to hear

B．hearing

C．to be heard

D．being heard

中国药典检查对氨基水杨酸钠中的间氨基酚，采用的滴定液是

A．氢氧化钠滴定液

B．盐酸滴定液

C．高氯酸滴定液

D．亚硝酸钠滴定液

E．乙二胺四醋酸滴定液