1 . All our officers are trained to ________(defense) themselves from knife attacks. (所给词的适当形式填空)

2 . Spare no effort to a___________knowledge and never get discouraged. (根据首字母单词拼写)

3 . The boys made an attempt ________ (leave) for camping but were stopped by their parents. (所给词的适当形式填空)

4 . It was the professor rather than his assistants that was _______(blame)for the failure of the experiment. (所给词的适当形式填空)

5 . The meeting is intended to p__________ an understanding of different countries in Asia.