Mary spent half an hour on play the piano 这句话不对吗?应该怎么该?

Mary spent half an hour on play the piano 这句话不对吗?应该怎么该? Mary spent half ____ hour doing ____ work.A.a;an B.an;a C.a;the D.an;the I spent half an hour_______my book. I spent half an hour ___(finish) my homework. I spent half an hour in doing my homework i spent half an month reading the book什么 He spent half an hour___computer games yesterday everyonekkkk they spent half an hour on talk是什么基本句型 We spent half an hour writing it.(%u63D0%u95EE%uFF09 I spent half an hour swimming 这句话对吗? he spent half an hour swim.=It( )( )half an hour( )( ). I spent half an hour on my homework yesterday.（保持原意l ( )half an hour ( )my homework skirt. 英语I spent half an hour getting to the shop.改为同义句：( )( )( )half an hour( )( )to the shop. I spent half an hour getting to the shop改为同义句 I spent half an hour___my homework.Afinish doing Bto finish doing Cfinishing to do Dfinishing doing I spent half an hour on my homework yesterday.（保持原意） I spent half an hour geting to the shop.的同义句 I spent half an hour writing the letter 改为同义句