the book if you are free, and you will learn a lot about how to study English .
ARead
B. Having read
C. To read
D. Reading
网友回答
(答案→)A. Read
B. Having read
C. To read
D. Reading
解析：考查固定句型。固定句型：祈使句+连词+陈述句，转换而来。祈使句+连词+陈述句=If引导的条件句+主句。这个句型进一步转换成：名词短语+连词+陈述句。句意：如果你有空，请读这本书，你就会从中学会很多关于如何学习英语的知识。故A正确。