222. In Paris nowadays, we may see musicians performing in the streets to ______.
In a courtroom it is sometimes difficult to ______ who is innocent and who is guilty.
Future will be a marvelous world of artificial ______----- robots might have their emotions and we human beings might have robots as friends.
As second-hand smoking is more harmful and dangerous, people want a total _____against smoking in public.
-- I didn't realize how popular the restaurant was until I made a reservation the other day.-- I beg your pardon, but when __________?
It_____ have been Tom that parked the car here, as he is the only one with a car.