During the Second World War, once before, the U-boats had been _____ because of air attack.
Kong Xiangdong became a great pianist in ___1980s when he was only in _____teens .
The speaker spoke at the meeting for 2 hours without _____ his notes.
The well-known performer our Chinese fans often referred ______ at our school yesterday.
It remains _____ whether he will have qualification(资格) to play in the finals.
______ running, learning English also needs skills .