问题
选择题
It has been 10 years _____ the population reached five billion. [ ]
A. since
B. when
C. that
D. before
答案
答案：A
搜题请搜索小程序“爱下问搜题”
It has been 10 years _____ the population reached five billion. [ ]
A. since
B. when
C. that
D. before
答案：A