1、
A good teacher should be able to infect his students with his own keenness for his subject.
一个好教师应能以自己对本学科的热爱来影响学生.
《简明英汉词典》
2、
The scabbard is content to be dull when it protects the keenness of the sword.
刀鞘在保护刀的锋利时,自己也满足于自己的驽钝.
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