某物体同时受到两个在同一直线上的力F₁、F₂的作用，物体由静止开始做直线运动，其位移与力F₁、F₂的关系图像如图所示，在这4m内，物体具有最大动能时的位移是(     )

澳大利亚的气候特征主要是（　　）

工业炼铁是在高炉中进行的，高炉炼铁的主要反应是：

①2C（焦炭）+O₂（空气）2CO②Fe₂O₃+3CO2Fe+3CO₂

该炼铁工艺中，对焦炭的实际使用量要远远高于按照化学方程式计算所需其主要原因是（　　）

    Many students ask for advice about improving (提高) their English. There are three basic(基本的) questions.
    The first question is about real English. Li Hao from Hubei wrote, “I enjoy watching English films and listening to real English songs. But it takes a long time. What do you think?”
    This is a great way to learn English! Talk about the film or song with your friends, and guess the meaning of the new words. Just enjoy yourself!
    The second question is about speaking. Sam, from Suzhou wrote, “Our school has a foreign teacher. But I'm shy and can't speak to her. What should I do?”
    When I visit China, lots of people in the street say, “Hello! How are you? Where are you from? Do you like China?” These are good questions to start a talk. Many people are shy when they speak English, so before you begin, take a deep breath and smile! Smiling always helps.
The third question is about vocabulary. Oliver, from Anhui wrote, “I want to remember all the new words. I write them down, but I forget them quickly. What should I do?”
    Try to remember eight or ten words a day. Write them on pieces of paper and place them in your bedroom. Say the words when you see them, and change them every day. And when you’re shopping, how about counting the English words, or saying the English names for everything you see?