It’s when you are out of cellphone range and farthest from help when you’re going to need urgent assistance. Think of being aboa

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问题     It’s when you are out of cellphone range and farthest from help when you’re going to need urgent assistance. Think of being aboard a boat sinking at sea, or crashing a motorcycle in the desert while on a camping trip.
    That’s what satellite phones are for—they send a signal directly to a satellite from anywhere with a clear view of the sky without need of a cell tower. But with per-minute fees of $ 1 or more, you’ll still need a regular mobile phone for everyday use. That means you need two phones. Just what you want when hiking—two weighty pieces of hardware to tote (随身携带). But now there is a hybrid (合成的)mobile-satellite phone, a single device that can connect to either network. Called the TerreStar Genus, this phone is available through AT&T for $ 1 070. As with any hybrid, compromises are made. For one, the mobile phone portion runs on the clunky Windows Mobile 6.5.3 operating system, so there isn’t the intuitive ease of the newer Windows Phone 7 system.
    Using the satellite side of the phone also requires some adjustments. Because the phone has no external antenna (天线), you have to hold the phone just so, or your palm will block the signal. You also have to make sure the phone is oriented toward the TerreStar-1 satellite at 111 degrees west. Also make sure to listen to the phone using the ear nearest the satellite, as your head can block the signal, along with mountains, trees or buildings.
    Some of those issues can be addressed with a $ 300 optional external antenna, but that adds more bulk. Even with the antenna the Genus is limited to North America and up to 200 miles offshore. Service excludes Mexico and Canada, but Canada is within range, and will be offered later, said TerreStar.
    Another thing to get used to is the time lag. It can take up to two minutes for the phone to initialize (初始化), acquire and connect to the satellite. You do get audible alerts to let you know the phone is working on it. When you get the connection, there are pauses between the time you speak and the listener hears what you say, much like first generation VoIP calls. The reason is that the satellite bouncing your call is 22 000 miles or more away. All of that sophisticated hardware takes a toll on the batteries. In satellite mode expect 4 hours of standby time and 1.3 hours talk time.
    TerreStar said the phone is made with first responders in mind—firefighters and the police who need communications in an emergency when cell towers might be out. But it is also an option for anyone who wants the security of a communications backup system—and is willing to pay for it.
According to the passage, we can infer that the satellite phone______.

选项 A、can be widely used to provide urgent assistance for people
B、provides service in a limited area
C、is so cheap that many people can pay for it
D、has external antenna with large bulk

答案B

解析 细节推断题。第四段最后一句指出,卫星电话的服务没有面向墨西哥和加拿大,从中推断出卫星电话的服务范围有限,所以答案为B)“在有限的范围内提供服务”。
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