2011年1月11日，我国自主开发的歼20 “隐形飞机”在成都首飞成功．歼20的机身呈菱形，能使反射的电磁波偏离接收它的雷达．它的表面采用新的雷达吸波材料制作，能吸收来自雷达的能量．对歼20“隐身”的原因，下列说法正确的是（）
①坚持民族区域自治制度也是在维护我国的国家安全
②坚持民族区域自治制度，能够更好的维护我国国家统一
③坚持民族区域自治制度就是要让各民族自行决定本民族一切内外事务
④只有坚持民族区域自治制度，才能保障平等友善共同繁荣的民族关系。
My name is Chen Lan. My home is in Gulangyu. Do you know it? It is in Xiamen. It is near the sea(海). Gulangyu is a small place，but it is very nice and clean. There are no cars，no buses. People only walk. So it is very quiet. Our house is in the middle of Gulangyu. Behind our house there is a big old tree. My grandfather tells me that the tree is very，very old. There are many birds in the tree. We call it a “bird tree”. Our house is near the sea. The sea is big and blue. There are a lot of fish in the sea. After school，I go there and catch(捉) fish with my friends. It is very interesting. I like fish and I like catching fish.
