They passed a factory, ________ there were rice fields.

1. A.
   whose back
2. B.
   at the back of it
3. C.
   at the back of which
4. D.
   at the back of that

They passed a factory, ______ there were rice fields．

[    ]

A．at the back of it　　   B．at back of which

C．at the back of which    D．at whose back

They _______ a factory, __________ there were rice fields.

[    ]

A. pass; whose back　　 

B. past; at the back of it

C. passed; at the back of which

D. passing; at the back of that

[　　]

A． whose back　　　　　　B． at the back of it

C． at the back of which　　　D． at the back of that