请根据下面短文回答第11～15题：
Reading for pleasure is the easiest way to become a better reader in English. It is also the most important way.
Some students say they don’t want to read for pleasure. They say they want to use their time to learn the rules of the language and new words. They say that pleasure reading is too easy.
Many experts(专家)say pleasure reading is very important for learning English. Dr. Stephen Krashen, a famous expert on learning languages, says that pleasure reading helps you learn many important things about English. Students learn more grammar and more words when they read for pleasure. They also learn more about good writing.
Dr. Krashen tells us that pleasure reading helps each student in a different way. Each student needs to learn something different. Pleasure reading makes it possible for each student to learn what he or she needs.
Reading for pleasure is not the same as studying. When you read for pleasure, you choose your own books, and you don’t have to remember everything. There are no tests on your pleasure reading books. Pleasure reading will help you:
—learn how English speakers use English
—read faster in English
—find examples of good writing in English
—learn new words
—learn about the cultures(文化)of English speakers

If you want to easily become good at reading, you should______.
[A] do pleasure reading
[B] read a lot of grammar books
[C] read many story books

卷筒出现下述哪种情况时，应报废（）。

A.裂纹；筒壁磨损达原壁厚的20％

B.筒壁磨损达原壁厚的20％

C.筒壁磨损达原壁厚的10％

D.筒壁磨损达原壁厚的15％