snow是不是可數名詞

　　He brushes the snow off his windows.

　　他把窗戶上的雪掃掉。

　　The pupils are sweeping away the snow.

　　小學生們正在掃去積雪。

　　Trekking through the snow with a sledge.

　　拖著雪橇在雪地里跋涉。