A-A+
A．It's very expensive.B．It hasn't proven to be
问题详情
A．It"s very expensive.
B．It hasn"t proven to be totally effective.
C．It can be damaging to some books.
D．It can"t be used on books published before 1850.
参考答案
正确答案：A
解析：What does the man say is a drawback to the process of restoring books?
