B

    Last week, scientists said they discovered a new birdlike dinosaur. With feathers, a beak (鸟嘴) and long legs, it looked pretty funny. This kind of dinosaur was 3 meters (10 feet) long, and it was higher than most humans. It also had sharp claws (爪子).

    Fossil hunters dug out the bones of this species in a rocky place of southwest North Dakota. The scientists nicknamed this dinosaur the "Chicken from Hell". They also gave it a more formal name: Anzu Wyliei. Anzu was a mythical (神秘的) fire-breathing bird. Wylie is the dinosaur-loving grandson of a man who supports the Carnegie Museum of Natural History in Pittsburgh, Pa. Scientists at that museum were part of the team that told the new dinosaur in a paper published on March 19 in the journal PLOS ONE. "The Anzu dinosaur is based on a surprisingly nice specimen(样品), and past digs turned up this animal," a scientist told Science News for Students.

箭靶

一天，小青和叔叔一同去了射击场。小青仔细看看靶子，原来箭靶是由10个同心圆组成的(如右图)。已知这个靶上面相邻的两个同心圆半径之差等于最里面小圆的半径。最里面的小圆叫做10环，最外面的圆环叫做1环。他很快运用学到的知识，算出了10环面积是1环的几分之几。

小朋友们，你会算吗？答案是多少？