请问为什么用covering ：seen from the moon,our earth ,with water covering
问题描述：
请问为什么用covering ：seen from the moon,our earth ,with water covering
_______ from the moon,our earth with water ______ twenty percent of its surface,appears as a blue ball.
a.Seen,covered b.Seen,covering
.第一空我懂 ,想知道cover为什么用ing ,不是被水覆盖的吗?
答
第二问是考with 的复合结构.动词的现代分词表主动,水是主动覆盖在地表的,按照你的理解,twenty percent of its surface is cover by water.
而此句是water covers the twenty percent of its surface.