the teacher encourages us to speak English as much as possib

因为as...as是两者进行比较,而实际上【as much as possible】
是【as much as it is possible】的省略,所以【possible】不是修饰speak,而是修饰【it is】
【much】才是修饰【speak】
翻译：我们老师鼓励我们尽可能多说英语.