阅读下列短文，从每题所给的四个选项（A、B、C和D）中选出最佳选项。

    Four seasons make a year. They a re spring, summer, autumn and winter. 

    Spring is a beautiful season. It's from March to May. In spring, trees turn green and flowers come out. Everything looks new.

    Summer is a happy season. It's from June to August. The weather is hot, so people usually wear cool clothes, go swimming and eat ice cream.

    Autumn is a colourful season. It is from September to November. In autumn, leaves on trees turn yellow. Sometimes they are yellow and red. The colours are beautiful.

    Winter is the last season. It's from December to February. In China, the weather is not the same in winter. In Beijing, it's very cold. It often snows. People often play with snow and go skating in rivers and lakes. Skating is their favorite sport in winter. But in Haihan, it's not very cold. It's very warm. People there can go swimming in the sea.

在函数$y=\frac{x}{x-2}$中，自变量x的取值范围是____ ．

若方程 =0有增根，则增根可能是（　　）

白鳍豚是我国特有的珍稀水生动物，在长江里生存繁衍了两干多万年．然而近几十年来．它们的数量迅速减少．导致白鳍豚走向绝灭的主要原因是（　　）

给下面加下划线的字注音。