题干

X、Y、Z、M是4种短周期元素,其中X、Y位于同一主族,Y与M,X与Z位于同一周期。X原子最外层电子数是其电子层数的3倍。Z原子的核外电子数比X原子少1。M是同周期中半径最大的元素(除稀有气体元素),下列说法正确的是(     )

A:Y元素最高价氧化物对应水化物的化学式可表示为HYO3

B:氢化物的稳定性Z >X>Y

C:X、Y、Z元素的气态氢化物中,Y的沸点最高

D:四种元素简单离子的半径由大到小依次为Y>Z>X>M

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D

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    Global Positioning System (GPS) is now a part of everyday driving in many countries. It is a space-based system that provides position and time information in all weather conditions. GPS can help people get to where they want to go.____When this happens, the driver is often to blame. Sometimes a GPS error is responsible. Most often, it is a combination of the two.

    ____Barry Brown, a GPS technologist, took an incident as an example. His friend once flew to an airport in the eastern United States. There he borrowed a GPS-equipped car to use. He wrongly plugged in the home address in the west. It wasn't until he was driving for thirty minutes that he realized it. Mr. Brown says this is a common human error. But he says, “One problem is that GPS has a very small screen and it can just tell you the next turn.____”

    “The Normal and Natural Troubles of Driving with GPS” lists several areas where GPS can cause difficulties. They include maps that are outdated, incorrect or difficult to understand. ____GPS may fail due to these reasons and then lead to confusion for the drivers.

    Although GPS sometimes causes difficulties when people are driving, the most attractive point of this system is its 100% coverage on the planet. It is important for you to have to know what you are doing when you use GPS. You need to have the “ability” to be able to use GPS because it sometimes goes wrong.____

A. There are quite a few situations showing the problems of using GPS.

B. That means that it is not really telling you about going to the wrong place.

C. This space-based system is an important tool for civil and commercial users.

D. But sometimes it sends you to the wrong place or leaves you completely lost.

E. They also contain timing problems related to when GPS commands are given.

F. Advances in technology play an active role in modernizing GPS in many ways.

G. To make GPS well used, you need a good understanding of how drivers and GPS work.