在过去的二十世纪下半叶开始使用。

Use began in the last half of the twentieth century.

youdao

渐渐地，在二十世纪下半叶成员国数量增多了。

Little by little, the number increased during the second half of the twentieth century.

youdao

渐渐地，在二十世纪下半叶成员国数量增多了。

Little by little, the number increased during the second half of the twentieth century.

youdao