My mother (be ) a teacher for 20 years.
A middle school student invented a new robot last term.(改为被动语态)
A new robot by a middle school student last term.
The Chinese graduate became a star because of his speech at Harvard.(对划线部分提问)
the Chinese graduate become a star?
They like playing basketball in the club better than going home after school.(保持句意不变)
They playing basketball in the club going home after school.
Charlie is so young that he can't take the underground alone.(改为简单句)
Charlie is to take the underground alone.
George wants to be a tour guide at the Bund for foreign visitors.(改为一般疑问句)
George to be a tour guide at the Bund for foreign visitors?