You must give the pen to Tom this afternoon.改为You must( )( )

You must give the pen to Tom this afternoon.改为You must( )( )the pen this afternoon.
Jack could speak English at the age of nine.改为Jack( )( )to speak English at the age of nine.
He heard from me yesterday.改为He( )a letter( )me yesterday.
Zhang Hua is 18 years old.改为Zhang Hua is( )( )boy.