modal verb

 

can used as the past form of 'can' to talk about what someone or something was able or allowed to do

I couldn't see what he was doing.

 

possible used to talk about what is possible or might happen

The baby could arrive any day now.

 

ask used to ask someone politely to do or provide something

Could you lend me £5?

 

ask permission used to ask politely for permission to do something

Could I speak to Mr Davis, please?

 

suggest used to make a suggestion

You could try painting it a different colour.