—What’s your impression of the Great Wall?—Wonderful! Once       , it can never be forgotten.

Nuclear energy may be dangerous if                          

He went there, _____ some books and call on an old friend of his.

—Mr Black，what about my application?—Oh，I regret________you that it hasn’t been successful.

_______ greatly by what he had heard and seen, he made up his mind to stand on his own feet again.