Question

The Dongying-Hainan airline         for about 5 months. I have taken the flights three times

1. A.
   is open
2. B.
   has opened
3. C.
   has been open
4. D.
   has been opened

Answer 1

C
句意：东营——海南航线已经开通了五个月了。我已经乘坐过这个航班三次了。结合语境可知本句描述的是现在已经完成的动作，用现在完成时态。主语是动作对象，故用被动语态。选C。
考点：时态及语态