plain drifting

例句：

1. 1. The boat was plain drifting in the calm sea.
   这艘船在平静的海面上平直地漂流。
2. 2. The river plain drifted by the campsite.
   河流平直地流过露营地。
3. 3. The ship drifted away from the shore.
   船平直地漂离了岸边。