The drops came as major dam building projects were carried out along the Yangtze.

这一下降是由于长江沿岸的大型水坝建设工程导致的。

The group also says it has taken control of a major dam on the Tigris River.

该组织还宣称他们控制了底格里斯河上一个主要的大坝。

The White House says it is not yet known why a major dam in Ukraine collapsed.

白宫表示，目前尚不清楚乌克兰一座主要大坝坍塌的原因。

Ukraine is accusing Russia of blowing up a major dam and hydroelectric power station in southern Ukraine.

乌克兰指责俄罗斯炸毁了乌克兰南部的一座大坝和水电站。