sentences:  The two of them engaged in a sort of rivalry, frequently bickering and trying to outdo each other in their technical support of Sarah Jane.When Clyde secretly borrowed K9 in order to cheat on a school exam, he asked Mr Smith not to tell Sarah Jane and Luke; Mr Smith readily agreed and graciously thanked Clyde for taking K9.However, despite their animosity towards each other, Mr Smith once seemed to show genuine concern for K9 when it appeared the latter might've been broken beyond repair.