Consequently, it is often necessary to close a series of basins by means of sluices and thus maintain a constant water level in the closedport section.
因此有必要使用泄水闸来封闭一些港区，以保持封闭港区中的水位。
2
More than 500 residents of the port city remained cut off from their homes by the standoff, and local businesses and three nearby schools remained closed.
由于双方仍处于对峙阶段，这个港口城市超过500名居民滞留在外，商店和附近的三所学校仍然关闭。
3
If you provided a wrong sequence of knocks (or no knocks at all), you would receive a "Connection timed out" message, and the SSH port would remain completely closed with no sign of its existence.