单句语法填空 1 . Jacy pretended ________________(know) everything about it and said nothing. 2 . China will not attach itself ________ any big power. 3 . He was about to give up when a good idea began ____________(form) in his mind. 4 . My classmates and I have decided to organize some wonderful singing and dancing ____________(perform) for them , which will last about 3 hours. 5 . After the foreign guests got familiar ________ the Chinese traditional festivals, they liked to live in China.