阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卷标号为16--25的相应位置上。
A farmer once organized a competition between his dog and his rabbit. He dug a hole in one of his biggest fields, and hid a carrot and a bone in it. He wanted to see     animal would find them first.
The        (cheer) and optimistic rabbit threw himself into looking for the carrot,        (dig) here and there, totally convinced that he would find it. But the dog, after sniffing around for a bit,   (lie) down and began to complain about how difficult it was to find one bone in such a big field.
The rabbit dug     hours, and with every new hole the dog complained even more about how difficult this was, even for the rabbit.       the rabbit thought that each hole dug was one hole less that needed to be dug. When there was no place in the whole field       (leave) to dig, the rabbit dug a tunnel right to       the dog had been lying all the time. There he found the carrot and the bone.
This is how the dog lost the game. He had come to      right place at the very beginning but failed to find the bone      he only complained and didn't try at all.