On Halloween, children in America like to _____ as ghosts to frighten people.
Maintaining(维持) peace and stability of the South China Sea and the East China Sea will certainly ____ a more promising Asian-Pacific area.
---I’m afraid this question is beyond me.---______. Tell me what you think. There’s no wrong answer.
He _____ to participate in the school debate, but on second thoughts, he gave up the idea.
Miss Green won’t be available at 9 tomorrow morning, for she ____ a speech at that time.
Sometimes to get out of difficulty, one must change his way of thinking, or simply change his ____ towards a problem.