23. If you live in the country or have ever visited there, ______ are that you have heard birds singing to welcome the new day.
According to the latest research, getting enough sleep is _____to maintaining good health and reducing stress.
In the eyes of a policeman, it's a usually very dangerous to get close to the _____criminal. He may do anything he would to escape.
Nowadays, Internet shopping will really_____when people are sure that it is safe.
Every time I take part in a friend’s big party. I always go to talk to those who just sit alone so that they don’t feel_____.
Nokia has a family of low-cost mobile phones based on Google's Android operating system.