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

Angela and John picked up the marriage ____ after they met online several times, which was not sensible．

 She had an advantage over others because she had a good ________ of both Chinese and English. 

I'm afraid you have no _____ but to come along with us.

 Although we hadn’t met for twenty years, I recognized him ____ I saw him.