滑动变阻器是通过改变电阻丝接入电路的____ 来改变接入电路的电阻值，从而改变电路中的电流。一个标有“10Ω 2A”的滑动变阻器，它的阻值变化范围是____ Ω。

梅雨时节家家雨，春草池塘处处蛙

    You are in the park. There is a big shop next to the park. There is a school near here. It's on the left side of the street. Between the school and the bank there is a hotel. A hospital is near the bank. Walk down Queen Street, and you will see a theatre on the First Street.

①____    ②____   ③____  ④____  ⑤____

莲是一种水生植物．当条件适宜时，莲的种子﹣莲子的淤泥中开始萌发，萌发后长成的第一片中必须在几天之内破水而出，在水面上形成浮叶，否则莲会死亡．浮叶提供的有机物让淤泥里的幼体生根并长出一条地下茎，地下茎逐渐形成日后的藕．每小段藕之间同样可以长出叶，它们按照同样方式破水而出，最终形成了神奇的对称现象（如图）