问题
选择题
This question isn't easy. It's very _____. [ ]
A. difficult
B. difficulty
C. easy
D. not easy
答案
答案：A
搜题请搜索小程序“爱下问搜题”
This question isn't easy. It's very _____. [ ]
A. difficult
B. difficulty
C. easy
D. not easy
答案：A
（1）同步卫星的高度；