论文题最宜用来考查学生综合运用知识的能力。 ( )
参考答案:对
— What is our head teacher like, do you know?
— Oh, he is very kind _____ he looks very serious. [ ]
A. because
B. though
C. if
D. when
初体就是溶血素,所以有补体参加的反应,可以发生溶血。