单选题 When a new maths topic is introduced, ______.
A．students answer questions on the board.
B．students rely entirely on the textbook.
C．it is carefully and patiently explained to the students.
D．it is usual for students to use extra worksheets.

【正确答案】 C

【答案解析】[解析] 找到topic所在的原文，原文中slowly and with a lot of repetition and elaboration都是在说老师如何给学生讲解问题的，只有答案C符合。
A项说的是修改作业时的内容，并不是讲新课题时的；B项是拿C部分提到的课本无中生有出的一个答案；D项的课外辅导是E部分的内容。