Choose the letter A, B, C or D to complete the passage below

Robots ___________ (6) an important role in our life. They have changed people’s lives in many ways. First of all, they ___________ (7) time and human labor. Thanks to robots, we don’t have to spends days and months ___________ (8) repeated work. For example, to produce French fries, we need human ___________ (9) potatoes, wash, then peel, cut them into pieces and finally fry them all. If we have robots to do the task, we will save a lot of time and produce more products. Secondly, robots help to replace human in dangerous work. Now we __________ (10) human to do such work as mining minerals. It’s helpful because there have been lots of people lose their lives in such jobs. However, it’s costly to buy a robot.

(6)........................

• A. 
  play
• B. 
  plays
• C. 
  playing
• D. 
  to play