From VOA Learning English, this is In the News.
The search for a Malaysia Airlines passenger jet expanded this week. The airplane, a Boeing 777, disappeared last Saturday on a flight from Kuala Lumpur to Beijing. It was carrying 239 people. At first, the search was along its expected flight path.
But by week's end, crews had expanded the search across parts of southern Asia for any evidence of Malaysian Airlines Flight 370.
With satellites and other technology available, how can a plane as large as the "Triple-7" just disappear? Air safety expert John McGraw says it is easier than you may think.
"People are under the impression that every airplane, even when it's flying across the ocean, is observed on some kind of radar scope, with a human being looking at that scope. And it's just not the case. Radars don't reach that far."
But John McGraw says there are also a lot of devices inside the Triple-7 that can help searchers follow its movement. Systems in the aircraft send altitude, weather conditions, position and speed to air traffic controllers. There are also at least three ways the pilots can communicate with controllers. Another tool is the flight data recorder or "black box." If the plane is downed in the ocean, the black box sends out a signal that can travel up to three kilometers away.
Many people remember when a French passenger jet disappeared five years ago. Air France Flight 447 went missing as it flew from Brazil to Paris. Its wreckage was eventually found in the Atlantic Ocean.
Air safety expert John McGraw remembers the National Transportation Safety Board taking action after the French jet went missing. He says US officials called for continuous download of an aircraft's flight data recorder information in case of emergencies.
"In the past they haven't been able to justify installing that kind of equipment, because it's expensive, and because there hadn't been that many accidents where it would have come into play. This will certainly provide some additional motivation and there may be calls to do that."
Malaysia Airlines Flight 370 was last seen on radar above Vietnam and Malaysia. Air traffic controllers in both countries say they did not receive any message that the plane may have been in trouble. On Tuesday, Malaysian media reported that the Malaysian military had noted the aircraft flying toward the country's west coast. That is far from where controllers lost contact with the plane.
The next day, China released satellite images showing three large objects floating in waters between Malaysia and Vietnam.
But China later said it could not confirm the objects belonged to the missing aircraft.
The Wall Street Journal reported that the plane could have stayed in the air for several hours past the time of its last confirmed location. The newspaper later said that the plane continued to send information about its engines and performance to satellites for five more hours. That suggests Flight 370 could have remained in the air or was on the ground somewhere.
Why the signals stopped is unclear.
This is a developing story. For the latest news on the Malaysian airliner, go towww.kekenet.com.
And that's In the News from VOA Learning English. I'm Steve Ember.
1.expand v. 使扩张；扩大
Why not try to expand your story into a novel?
2.available adj. 可用的；有空的
Doctors have an armoury of drugs available.
3.impression n. 印象，感觉
She made a favourable impression on his parents.
4.altitude n. 高度，海拔高度
The airplane kept on flying at a high altitude.
5.eventually adv. 终于，最后
Our flight eventually left five hours late.
6.continuous adj. 连续的
She was in continuous employment until the age of sixty-five.
7.justify vt. 证明…有理
He made a half-hearted attempt to justify himself.
1.People are under the impression that every airplane, even when it's flying across the ocean, is observed on some kind of radar scope, with a human being looking at that scope.
同位语从句属于名词性从句，大多由从属连词that引导，常常跟在fact, idea, opinion, news, hope, belief等名词后面。同位语从句一般用来解释或说明这些名词的具体含义或内容，在逻辑上表现为同位关系 。例如：
They are familiar with the opinion that all matter consists of atoms.他们很熟悉这一观点，所有的物质都是由原子构成的。
They were delighted at the news that their team had won.当听到他们的球队赢了的消息时，他们欣喜若狂。
The factory(that)we visited yesterday is a chemical one.我们昨天参观的那家工厂是化工厂。(that在从句中作宾语，所以此句是宾语从句)
The news that he will leave for Shanghai is true.他将要去上海的消息是真的。(that只起连接从句的作用，所以此句是同位语从句)
2.If the plane is downed in the ocean, the black box sends out a signal that can travel up to three kilometers away.
send out发送； 发出
Send out a distress signal; the ship is sinking.
3.He says US officials called for continuous download of an aircraft's flight data recorder information in case of emergencies.
in case of万一；假如；假使
She had had the foresight to prepare herself financially in case of an accident.
本周，对失踪马来西亚航空客机的搜索范围扩大。这架波音777飞机上周六从吉隆坡飞往北京时失踪 。机上共有239人 。起初，搜索范围仅限于原定飞行路线 。但是搜索工作接近一周时，工作人员将搜索范围扩大至南亚部分地区，搜索马来西亚航空MH370航班的线索 。
“人们以为每一架飞机，即使在飞越海洋的时候，也是受到雷达设备监控的，而且有专人监测。实际上并非如此 。雷达并不能扫描到那么远的范围 。”
但是John McGraw表示，波音777飞机内也有很多设备可以帮助搜索人员追踪其活动。飞机内的设备可以向空中交通管制员传送海拔，天气状况，位置和速度信息 。飞行员还有至少三种方法可以跟管制员联系 。另外一种工具是飞行数据记录器，或者叫做“黑匣子”，如果飞机坠入海洋，黑匣子可以向远至3千米的范围发送信号 。
许多人记得五年前一架法国客机失踪时的情景。法航447航班从巴西飞往巴黎时失踪 。飞机残骸最终在大西洋上找到 。
空中安全专家John McGraw回忆说，这架法航客机失踪后，国家运输安全委员会采取了行动。他表示，美国官员要求连续下载飞机飞行数据记录器的信息，以备紧急情况 。
人们最后在雷达上看到马来西亚航空MH370航班是在越南和马来西亚上空。两个国家的空中交通管制员都表示，他们没有收到任何信息表明这架飞机可能遭遇困境 。周二，马来西亚媒体报道称，马来西亚军方曾经观察到这架飞机飞向西海岸 。这距离空中交通管制员与飞机失去联系的地方已经很远 。
华尔街时报报道称，这架飞机可能在最后证实的地点上空逗留了几个小时。这家报纸税后报道称，这架飞机随后向卫星传达引擎和性能信号长达五个小时 。这表明MH370航班在空中盘旋或在地面上某个地方 。但是为何信号会停止并不清楚 。
以上就是今天的美国之音慢速学英语新闻报道。我是Steve Ember 。