填一填．

1861年俄国改革以前，工业资本家30%是农奴身份，财产随时有可能被地主侵占。这一问题反映的本质是（    ）

已知 f(x)=a−$\frac{2}{3^x+1}$(a∈R) ：

2011年4月10日，我国在西昌卫星发射中心用“长征三号甲”运载火箭，成功将第八颗北斗导航卫星送入太空预定转移轨道。该火箭所用燃料是偏二甲肼（CH₃-NH-NH-CH₃）和四氧化二氮（N₂O₄）。在火箭升空过程中，燃料发生反应：CH₃-NH-NH-CH₃+2N₂O₄→2CO₂+3N₂+4H₂O，提供能量。下列有关叙述正确的是（ ）

阅读理解
    Hello, my name is Lina. I'm 10 years old. I'm wearing a red dress. Red is my favourite colour and dresses are my favourite clothes. I like to read books. Fish is my favourite food. Amy is my friend. She is 11 years old. She likes green and her favourite clothes are skirts. She likes to play ping­pong. She likes fish, too. But her favourite food is rice and vegetables. We like to drink juice.