电焊机外壳应设有良好的保护接地（或接零）装置，其螺栓不得小于M8，并有明显的（）（或接零）标志。

  同义句转换。

1. Here you can find out more about these world-famous  musicians.  

    Here you can find out more about these musicians _____ are _____ in the world.

2. Liverpool is very important because its industry and  trade played an important role in the 18th century.  

    Liverpool is very important _____ _____ its industry and trade in the 18th century.

3. They sleep outdoors in tents and listen to the music.  

    They sleep _____ _____ _____ _____ and listen  to the music.

4. Tourists can take a bus tour to visit some of the places  the Beatles mentioned in their songs.  

    Tourists can take a bus tour to visit some of the places _____ the Beatles _____ in their songs.

5. Open-air rock concerts are liked by many people.   

    Open-air rock concerts are_____ _____.