Read and write. 你能根据汉语提示，找出藏在字母串里的单词吗？   

1. scatoa (猫)                               

2. fbdogfge (狗)                               

3. lfjkducko (鸭子)                                

4. margoatbe (山羊)                                

5. jopsheepal (绵羊)                              

往复式压缩机活塞的结构有哪几种形式？