问题
Have you heard of Earth Day — Yes, We have only one Earth. We haveno choice but ________ it.
A: protect
B:protected
C:protecting
D: to protect
B:protected
C:protecting
D: to protect
正确答案是：
同类题型
Does English every day help a lot — Of course.
________ , I know it doesn’tmatter.
Theyfirstreachanagreementonthebasicprinciple,thedetails____later
Did you receive the letter the next day?—No Somehow, it was three weeks ________ I received it
When will the railway that connects the two cities open—_____ next year.Only two thirds been built.