Only if you put ______ sun there did the movements of the other planets in ______ sky make sense.

A．the; 不填

B．the; the

C．不填; the

D．a; the

某种烃与H₂1:1加成后的产物是:   ,则该烃的结构式可能有（  ）

A．1种

B．2种

C．3种

D．4种