He has called several times this morning; _____ there is something very important.

Playing on a frozen sports field sounds like a lot of fun. Isn’t it risky, ______?

—Must I turn off the gas after cooking ? --Of course . You can never be ___ careful with that.

---- Do you think it's a good idea to make friends with your students? ---- _____ , I do．I think it's a great idea．

— I hear your dad is ill. Is he ____ better? — Thanks. He’s fine now.