句型转换 根据括号内的要求改写句子，在答卷相应的横线上填写答案，每空限填一词。（本大题共5分，每格0.5分）
They have already finished the work. (改为否定句)
They ________ finished the work ________.
Lucy came here two days ago.(用 for two days 改写)
Lucy _________ _________ here for two days.
Tom has been at this school since he came to China. (划线提问)
_________ _________ has Tom been at this school?
Seeing the huge glass ball falling through the darkness is exciting.(改为同义句)
_________ _________ _________ ________ see the huge glass ball falling through the darkness.