语法填空（共10小题：每小题1.5分，满分15分）
阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。
In the 1950s, a family that owned a farm near Beulah, Michigan kept a bull chained to an elm (榆树). The bull paced around the tree, dragging the heavy iron chain,
led to a groove (槽) in the bark. The groove was deepened over the years. Though for whatever reason,        did not kill the tree.
After some years, the family took their bull away. They cut the chain,      (leave) the link around the tree.
Then one year, agricultural catastrophe       (strike) Michigan in      form of Dutch elm disease. All of the elms lining the road leading to the farm became infected died. Everyone thought that the old elm would be the      . The farm owners considered      (go) the safe thing: pulling it out and chopping it up into firewood before it died.
       (amazing), the tree did not die. It’s said that what doesn’t kill you will make you stronger. Or,       a plant pathologists (病理学家 ) put it , “Life breaks us all, but afterwards, many of us are strongest at the broken places.”