要测量河两岸相对的两点A、B的距离，先在AB的垂线BF上取两点C、D，使CD=BC，再定出BF的垂线DE，使A、C、E在同一条直线上，如图，可以得到△EDC≌△ABC，所以ED=AB，因此测得ED的长就是AB的长，判定△EDC≌△ABC的理由是（　　）

阅读理解

    A new study suggests that washing dishes by hand is healthier than using a dishwasher.

    Nobody likes doing the dishes, but it turns out that doing this task might pay off in an unexpected way. According to a new study published in the Journal of Pediatrics, washing dishes by hand instead of using a dishwasher might prevent the development of allergies (过敏).

    Researchers in Sweden surveyed the parents of 1,029 children aged 7 and 8. They discovered that children whose families hand-washed the dishes instead of using a machine were less likely to have allergies.

    Earlier research has shown that dishes washed by machine are cleaner than those washed by hand. So why would kids who eat with slightly dirtier plates be better when it comes to preventing allergies? One explanation is based on a theory known as the “hygiene hypothesis,” which says the reason why kids develop allergies is that their environment is actually too clean. Your immune system keeps you healthy by fighting germs like viruses and bacteria. But when you have allergies, it overreacts and tries to fight ordinary things like pollen(花粉) or certain foods.

    Being exposed to germs, especially early in life is good training for the immune system, says the lead author of the study, Dr. Bill Hesselmar of Queen Silvia Hospital in Sweden. “You stimulate the immune system in various ways and it becomes tolerant.”

    This study shows that while using the dishwasher might be easier, the old-fashioned method of cleaning up could be better for your health.

“大洋一号”第22航次自2010年12月8日从广州启航，于2011年11月11日返回青岛，完成我国最大规模环球大洋科考，如图为此次科考的路线示意。据此回答下题。

   “Cool”is a word with many meanings．Its old meaning is used to express a temperature that is a little bit cold．As the world has changed，the word has had many different meanings． 
   “Cool”can be used to express feelings of interest in almost anything．
   When you see a famous car in the street，maybe you will say，“It's cool．”You may think，“He's so cool，”when you see your favourite footballer． 
   We all maximize（扩大） the meaning of“cool”．You can use it instead of many words such as “new” or “surprising”．Here's an interesting story we can use to show the way the word is used．A teacher asked her students to write about the waterfall（瀑布）they had visited．On one student's paper was Just the one sentence，“It's so cool．Maybe he thought it was the best way to show what he saw and felt． 
   But the story also shows a scarcity（缺乏）of words．Without “cool”，some people have no words to show the same meaning．So it is quite important to keep some credibility（可信性）．Can you think of many other words that make your life as colourful as the word “cool”？ I can．And I think they are also very cool．