因跑道上有障碍物，导致一架B737在高度30米复飞，构成（）。
参考答案：飞行事故征候
Which city is _____ from Beijing, Shanghai, Hangzhou or Nanjing?[ ]
A. far
B. farther
C. farthest
D. the farthest
The No. 15 bus stops here, ______?
A．isn’t it
B．is it
C．doesn’t it
D．does it
