“鱼儿离不开水”，下列不属于鱼类适应水生生活的特征是（　　）

《赠从弟》中作者借物喻人，表现劝勉之意的中心句是：____，____。

    I' m Jiang Ling from Hangzhou and I' m in Class 2. There are forty-five students in my class — twenty boys and twenty—five girls. I have got two good friends. One is Hu Ning. He is on my left. He is good at maths. The other is Tu Guo. He is on my right. IT is his favourite. After school, we usually read in the library or work on the computer. Now we are having a history lesson.

    I'm Paul from London and I'm in Class 4. There are twenty-two students in class — twelve girls and ten: boys. Tim is my good friend. He is behind me. He is tall and he is good at PE. We usually play basketball on Friday afternoon. Now it's cool. We're playing basketball in the playground.

“天宫一号”于2011年9月29日在酒泉卫星发射中心成功发射。它的发射标志着中国迈入中国航天“三步走”战略的第二步第二阶段。火箭发射所用的燃料是四氧化二氮（N₂O₄）。下列叙述中，正确的是（）

—I think it is enjoyable,     I sometimes have some trouble in study.