i dont know who the watch belongs to

i dont know who the watch belongs to "i dont know who is the boy" & "i dont know who the boy is" do you know who the computer belongs to I dont't know whom this backpack belong to 还是 belongs to who are the two__(act) Dorry,i dont know. 怎样翻译合适：who the watch belongs to was lost is unknown. who the watch belongs to was lost is unknown 句子成分分析 i dont know who am i I want to know who ____my watch?(find) i dont want to know 改同义句Do you know who the computer belongs to?Do you know____ Do you know who the pen belongs to?belong后为什么加s?