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。

    Last Friday, as usual I went home by bike. But at a crossing, I ____ (sudden) knocked an old man off his bike. I hurried over and found that his leg ____ (injure). Nervous and worried, I called my mom and told her what had happened. We decided to take him to the hospital first.

    Shortly after we arrived at the hospital, my mother came. I had some doubt ____ there was anything seriously wrong with the old man. The doctor gave the old man a ____ (detail) examination. To our delight and relief, there was nothing seriously wrong with him. We thanked the doctor and left. After that, we went back to the place ____ the old man's bike was parked, only ____ (find) it didn't work. So I immediately found a repairman to get it ____ (fix). Soon he finished ____ (repair) it. Before the old man left, my mom offered him our cell phone number in case he needed to contact us. Then the old man got on his bike and we waved goodbye to each other.

    If I ____ (ride) my bike carefully, I would have avoided the accident. Consequently, the unexpected accident made me realize that in the first place we should be careful, but once it occurs, we should take ____ (responsible).