阅读下面短文，从短文后各题所给的A、B、C和D四个选项中，选出可以填入空白处的最佳选项，并在答题纸上将该项涂黑。

On the last day of college before graduation, our professor walked up on stage to give us a 41   lesson, which she called "a life lesson on the   42   of mindsets（思维模式）”. As she raised a glass of water over her head, everyone  43    her to mention the typical "glass half empty or glass half full” question.  44   , with a smile on. her face, the professor asked, “How 45    is this glass of water I'm holding?'，Students shouted out answers 46   from eight ounces（盎司）to a couple pounds?

After a few moments of reasonable answers, she replied, "In my opinion, the 47    weight of this glass doesn't matter. It all  47   how long I hold it. If I hold it for a minute or two, it's fairly 49    . If I hold it for an hour   50 , my arm might feel painful. If I hold it for the whole day, my arm will feel completely numb,    51    me to drop the glass to the floor. In each   52  , the weight of the glass doesn't change,     53     the longer I hold it, the heavier it       54      to me."

As the class nodded their heads in  55 , she continued, "Your worries, disappointments, and   56   thoughts are like this glass of water. Think about them for a while and     57   happens. Think about them a bit longer and you begin to feel 58  . Think about them all day long, and you will feel completely numb,   59    to do anything else until you     60  them."