I think _________ of the materials I listened to at the beginning of the exam __________ easy.

A．two thirds; is

B．second three; are

C．two thirds; are

D．two third; are

夸美纽斯的《大教学论》的问世，使教育学从以往的哲学、社会学等论述中分化出来，成为一门独立的科学，他本人也被尊崇为教育史上的哥白尼。