阅读下面短文，在空白处填入一个适当的词，或填入括号中所给单词的正确形式．

     A group of boys were playing basketball in the park． The playground was great，（1）　　 there was no fence（栅栏）around it．If one boy missed the ball， someone had to catch it at once， so it wouldn't go too far away．

     One boy threw the ball too hard and it flew like a rocket over the （2）　　（head）of all the other boys， and kept on flying．

      Anna was sitting nearby and watching the ducks swim in the river． Suddenly， she （3）　　（hear）some shouting and turned to see a big， orange object coming towards （4）　　（she）．

     "Stop the ball，" one of them shouted．

     The ball landed close to the river． The ducks flew away quickly．

     Anna opened her arms， just in time （5）　　（stop） the ball as it was going to fall into the river．

     "Could you please bring it over here？"asked one boy （6）　　（polite）．

     Anna walked to them with the ball． She was nervous because the boys were （7）　　（old） than her． However， they were very nice and thanked her （8）　　 saving the ball．

     "Can I join you？" Anna asked．

     The boys agreed， but they were not sure （9）　　 she could throw the ball even close to the basket．

     Anna took the ball and then had （10）　　 try． The boys watched in surprise as the ball went straight into the basket． Anna smiled as the boys cheered loudly for her．