Teachers have to constantly update their knowledge in order to maintain their professional ____. 

The fridge is _____for one year. It means that the company that makes it promises to repair or replace it if it breaks within a year.

Thank god，you finally returned home ________.You can never imagine how I worried about you when I was told about the terrible accident.

 No product is allowed to go into the market if it fails to _____ the quality standard. 

Mr. Huang will ________ in the movement.