he responded with great anger ________this unfair treatment of his classmate填什么?
问题描述：
he responded with great anger ________this unfair treatment of his classmate填什么?
答
FOR,因为原文意思应该是因为他对他的同学对他的不公平对待，所以很气愤的回应。
FOR 是承接下半部分的，FOR的意思是因为
答
to
respond to...对...的回应