问题
操作题
请标出通电螺线管两端的极性，并画出图中放置的小磁针北极在螺线管通电时的受力方向（黑色部分表示小磁针的N极）。
答案
搜题请搜索小程序“爱下问搜题”
请标出通电螺线管两端的极性，并画出图中放置的小磁针北极在螺线管通电时的受力方向（黑色部分表示小磁针的N极）。
| 阅读下面一篇材料，从所给的A-G七个选项中，选出正确的选项填空，使短文通顺、内容完整。 | |
| People all over the world do shopping in supermarkets. Who decides what you buy in the supermarkets? 1._____________ When you go into the supermarket, you see shelves full of things.2.______________You pull a shopping cart and put the things you choose in it. If you hear soft and slow music, you may walk slowly. If you hear fast and loud music, you may walk quickly. 3._____________You walk slowly and have more time to choose things. Suppose you go to the meat department first. 4._____________The cheaper meat is at the other end of the meat department, away from where the customers enter. You have to walk by all the expensive meant before you find the cheaper one. 5.______________. That's some knowledge of supermarket science. Many supermarkets use such knowledge to make customers stay longer and buy more.
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