题干
Great________have been made to make our environment more and more beautiful.
A：efforts
B：pains
C：trouble
D：attempt
答案(点此获取答案解析）
A
Great________have been made to make our environment more and more beautiful.
A：efforts
B：pains
C：trouble
D：attempt
和
，地球表面的重力加速度为g，则火星表面的重力加速度约为
