42. The passage mentions that the grade F was once banned at ______

49. What step is essential to the traditional production of flu vaccine?

34.

33.

27.

14.I’m glad to hear that John finally ________ his own mistakes.

2. _________ it is possible that genes have some influence, I find it hard to believe that they would count for more than all the thousands of experiences each person has.

38.

10.Traditionally, Chinese are written _______ in columns going from top to bottom and ordered from right to wrong.

16.Today, these methods are viewed as practices that can cause harm and are in the last -_______ only to be used when measures have failed and safety is at sever risk.

31.张老师认为教育就是为了要让学生学习知识，把握学习内容。张老师遵循的理论是（ ）。

25.