---        was it         they discovered the entrance to the underground palace?

--- Totally by chance.

A．What; that                  B．How; that            C．When; how          D．Where; that

---____ was it _____they discovered the entrance to the underground palace?

--- Totally by chance.

A．What; that       B．How; that C．When; how      D．Where; that

- ______ was it _______ they discovered the entrance to the underground palace?

- Totally by chance.

A．What; that         B．How; that            C．What; when         D．How; as

—______was it ______ they discovered the entrance to the underground palace?

—Totally by chance．

A．How, that       B．What, that          C．When, when        D．Where, that 

—How was　 ________ they discovered the entrance to the underground palace?

—Totally by chance.

A．he that　　　　 B．it that　　 C．it when D．he which