用适当的代词补全对话,每空一词 Cindy:Where's my pen?I can't find ( ). David:Hey,here's a pen!Is this pen ( )? Cindy:No,it isn't ( ).( )pen is here.You can ask Mary. She lost ( )this morning. David:Mary,is this ( )pen? Mary:No,( ) is white. Jin lost ( )pen,too.You can ask ( ). David:Yes,it's Jim's pen.( )is black.And look!It has the name “Jim” on it.