The mummy is that of Shepenmut who was once a singer in the

The mummy is that of Shepenmut who was once a singer in the Temple of Thebes.
上面那句是新概念英语2册77课原话,意思是：这是曾在底比斯神殿里当过歌手的塞潘姆特的木乃伊.
请问能否改成：The mummy of Shepenmut who was once a singer in the Temple of Thebes.就是说能否把is that去掉.
因为还有一句话：The mummy of an Egyptian woman who died in 800 B.C has just had an operation.这句话就没有is that
再请问：应该读成“is that”还是“that of”
我感觉“is that of”放在一起怪怪的.