In 1959, the RAND Corporation held several conferences on Deep Underground Construction.

1959年，兰德公司在对深地下施工方面﹐举行了多次会议。

youdao

In 1959, the RAND Corporation held several conferences on Deep Underground Construction.

1959年，兰德公司在对深地下施工方面﹐举行了多次会议。

youdao