• A．to discover sentence patterns and grammatical rules
• B．to expand vocabulary
• C．to use the target language
• D．to encourage unsuccessful language learners to learn independently, actively and purposefully
• E．from clues
• F．to say strange things

The author wrote this text ______.

A．He has to justify his arrests while unable to provide sufficient evidence in most cases.
B．He has to provide the best possible public service at the least possible expense.
C．He has to get the most desirable results without breaking the law in any way.
D．He can hardly find enough time to learn criminal law while burdened with numerous criminal cases.

A．on
B．for
C．with
D．of