问题：
Has ____ how many spies we caught during the war ____ up to now?
A.it been declared; have been set free
B.it declared; have been set free
C.they declared; has been set free
D.they declared; have set free
Has ____ how many spies we caught during the war ____ up to now?
A.it been declared; have been set free
B.it declared; have been set free
C.they declared; has been set free
D.they declared; have set free
A.it been declared; have been set free
B.it declared; have been set free
C.they declared; has been set free
D.they declared; have set free
参考答案：