I think we have solved this problem once and for all.
Giải chi tiết:
once and for all = ngay lập tức hoàn thành
A. vĩnh viễn
B. tốt
C. tạm thời
D. cuối cùng
Population growth rates vary among regions and even among countries within the same region.
Around 150 B.C. the Greek astronomer Hipparchus developed a system to classify stars according to brightness.