There are still many problems ______ before we are ready for a long stay on the

题干

There are still many problems ______ before we are ready for a long stay on the Moon.
A. solving B. solved
C. being solved D. to be solved

上一题下一题 0.65难度单项选择更新时间:2016-07-12 04:51:04

小学学科试题库

初中学科试题库

高中学科试题库