With the nuclear crisis worsening in Iran, the world's attention is fixed again on ______is called the Middle East.

A．which

B．that

C．what

D．It

（）时，精密进近雷达管制员应当通知航空器复飞并说明原因。

A.航空器在五边出现危险情况

B.在有其它飞行冲突

C.在没有及时收到塔台管制员的着陆许可

D.A、B和C