张莉同学在做“观察叶片的结构”的实验时所看到的菠菜横切面如图所示，请你据图分析回答：

（1）制作徒手切片时常选取最____ 的一片观察；

（2）请据图分析，叶片正面颜色深、背面颜色浅的主要原因是____ ；

（3）光合作用需要的水分、无机盐运输到叶肉细胞以及叶片制造的有机物运出叶片都是通过____ ____ 实现的；

（4）⑥的张开和闭合受____ （填结构名称）控制．

实验室中常用分解过氧化氢来简便快速的制备氧气，化学小组Ⅱ进一步探究外界条件对过氧化氢分解速率的影响，并进行了氧气性质实验．

【查阅资料】有些水果、蔬菜对过氧化氢的分解有催化作用．

为了防止静电危害。下列措施中不当的是

    It is said that about half of the people in China smoke. Many young boys and girls have the habit of smoking, though they are middle school students.
    More and more people have come to realize how serious this problem is. But they are never bored with it. ①Some people think it is a kind of fashion, some think it is of great fun and others think that smoking can relax themselves.
    Smoking causes many illnesses. A lot of people always cough(咳嗽)②______ ______smoking. The most serious illness caused by smoking is lung cancer. At the same time smoking is a waste of money. Beside, careless smokers may cause dangerous fires.
    It's known that smoking does harm to our health. We should get rid of(摆脱) the bad habit of smoking.