在“构建和谐校园”的活动中，大明被评为“文明之星”你是他的好朋友，请用简短的英语对他

进行介绍，并写一句你最想地他说的话。

     Daming is my good 1________. He is quite friendly and helpful. He is always trying to help 2_______.

He does well in all his 3_________. And he has many different 4________ of hobbies. He is always

well-behaved. He sets us a good example. He is the hero in my heart.

     写一句你最想对他说的话：____________________________________________________

减小铸坯振痕的方法是（）。

A．高频率小振幅

B．低频率小振幅

C．低频率大振幅