In 1620,about half the USA__forest.In 1620,about half the USA__forest.A.was covered B.was covered by C.were filled with D.covered with如果D选项是be covered with呢

Question

In 1620,about half the USA__forest.
In 1620,about half the USA__forest.
A.was covered B.was covered by
C.were filled with D.covered with
如果D选项是be covered with呢

Answer 1

B
A 加个with
C 表示空间不表示平面
D 缺少谓语