Malaysia Airlines (马航) flight MH370 disappeared from radar (雷达) screens an hour after it took off on March 8.It has 1 for more than 3 months.

    The plane may fall into the sea. China，Malaysia and many other countries have joined to search the 2 on the sea. The relatives of the 227 passengers and 12 crew (乘务人员) are 3 good news from them.

    How did the accident 4？It is said that the plane was attacked (攻击) by the terrorists. Some think there may be something wrong with the plane，and others think the accident may be 5 by the mistake of the crew. However it is 6 to tell the reason because the plane hasn't been found yet.

    It may 7 some time to find the missing plane and even more time to get to know the truth of what happened. However，we can't stop imagining what happened to the plane 8 it is found.

    Whether the missing plane is found 9 not，the whole world should pay more attention to the safety of people，especially at airports.

    We hope these people on the plane will be 10，and they can get together with their family members.

汽油机是热机中的一种，如图所示是汽油机的 ____冲程，此过程是将内能转化为 ____能．已知某型号汽油机效率是30%，假设在汽油机内完全燃烧2kg汽油，所放出的这些热量通过汽油机的转化可以对外做　 ____J的有用功（汽油的热值为5×10⁷J/kg）．

函数y=a^x﹣1+2（a＞0，a≠1）一定经过的定点是（　　）