Question

______ needs further discussion to decide whether we will _______ the war operation.

1. A.
   It; join in
2. B.
   This; take part in
3. C.
   That; join in
4. D.
   There; attend

Answer 1

A
“whether we will join in the war operation” 是主语从句，放在句末时，要用it作形式主语。