骑自行车是一种既健身又低碳的出行方式，下列说法正确的是_刷题宝

题干

骑自行车是一种既健身又低碳的出行方式，下列说法正确的是（）

A：自行车轮胎上的花纹是为了增大摩擦

B：用力蹬车是为了增大车的惯性来增大速度

C：下坡时以自行车为参照物，车的坐垫是运动的

D：停在路边的自行车，它对地面的压力和所受到的重力是一对平衡力

上一题下一题 0.0难度选择题更新时间:2014-12-18 06:56:42

答案(点此获取答案解析）

A

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已知点P（x，y）在不等式组

{\begin{matrix} x - y + 1 < 0 ， \\ 2 x - y - 2 > 0 ， \\ 3 x - 2 y + 4 > 0 \end{matrix}

所表示的平面区域内运动，则

\frac{y}{x}

的取值范围为____．

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许多化学概念在逻辑上存在着包含、并列或交叉的关系，如图所示．下列有关概念间的关系的说法正确的是（）

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---Look. The man at the gate _____ be our headmaster. He is always standing there every morning.
---No. it ____ be him. He is having a meeting in the office now.

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下列四个几何体中，主视图与左视图相同的几何体有（）

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阅读下面的文章并按要求完成小题。
Root Vegetables

Would you like to eat a root? You probably already have. People and animals eat many kinds of roots. ①Most roots that people eat are usually called root vegetables. A root vegetable is what we call veggies that grow underground.

A carrot is one type of root vegetable. It is the orange, edible root of the carrot plant. ②to, many, in, like, people, salad, put, it(.) A turnip , is another root vegetable. It is a member of the cabbage family. Turnips are usually eaten boiled, steamed, roasted, fried, pickled, or even raw.

③Although some people do not consider potatoes to be a veggie, but they are a root vegetable.

People like to eat them mashed, boiled, and fried. Sweet potatoes, yams, beets, and leeks are some other root vegetables that people like to eat.

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