题目内容：

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卡相应位置。

Unprecedented Aviation Mystery

A Boeing 777 took off from Malaysia’s largest city of Kuala Lumpur at 0:41 am on March 8.

1._____destination was Beijing. But the flight never arrived, 2.______ （leave） friends and relatives of the passengers onboard weeping and worrying.

There were 239 people3.____   board the Malaysia Airlines flight，including China， Vietnam，the US，Singapore， and the Philippines 4._______ still ______ （search）for the missing plane.

Its 5.__________ （disappear）is an "unprecedented（史无前例的）aviation mystery”， Azharuddin Abdul Rahmanm，head of Malaysia’s Civil Aviation Authority，said on March 10.

There was no sign of 6.____   crash.

About two hours of after taking off，air traffic control suddenly lost contact with the plane. The weather was clear，the pilots didn't make any distress calls，7.       no debris 碎片） was found in the area 8.______ the flight last made contact.

Besides，airplane crashes9.________ （typical）occur during takeoff or landing. Only 9 percent of fatal accidents happen 10. ______ a plane is at cruising（平稳行进的）altitude，according to a report by Boeing in August.