没有干净的饮用水，许多社区根本无法生存。

Without access to clean water, many communities simply cannot ___exist.

干旱期间，村民们靠着能找到的少量水艰难生存。

During the drought, the villagers struggled to ___exist on the little water they could find.

即使在最严酷的环境中，某些生命形式仍能设法生存。

Even in the harshest environments, some forms of life manage to ___exist.