下列说法正确的是（   ）

如图，在一张不透光的纸上用针扎一个直径约1mm的小孔，让白炽灯泡发出的光穿过小孔射到白纸上，在白纸上可看到一个清晰的____的像，这是____现象．这是由于____产生的．向上移动小孔．像的大小变____．

短文阅读。    We have four seasons. They are spring, summer, autumn and winter. In spring, there are many flowers and green trees. I can play on the grass with friends. In summer, it's hot. I can swim in the sea and eat ice-cream. I like summer. In autumn, Farmers are busy. We can eat moon cakes in autumn. But I like winter best. In winter, it's cold. Sometimes it snows. I often skate in winter. Sometimes I make a snowman.
⑴~⑹Read and judge.读一读，判断对错。⑺完成表格。

利用某机械工作时，动力做的功是400J，其中额外功是100J，动力做的有用功是____J，机械效率是____．

下列属于鸟类特有的特征是（  ）

①体表有羽毛 ②用肺呼吸并用气囊辅助呼吸 ③体温恒定 ④通过产卵繁殖后代 ⑤前肢覆羽成翼 ⑥善于飞行．