To see a young couple loving each other is；but to see an old couple loving each other is the bestsight of all.

There is no doubt _______ international cooperation is the key to _______ with cyber crime.

During the week ____ he tried to collect materials for his article.

Ken, why do you look so tired?—I _____ myself _____ the climate since I came here.

When asked about his result of the driving test, David said with a big smile that he had.