Colin tried to swim after him, but the undercurrent swept them apart.科林试图跟在他后面游, 但一股暗流把他们冲散了。

There is a dark undercurrent in his songs.在他的歌曲中有一股黑色暗流。

There is a deep undercurrent of racism in British society.英国社会中有一股深深的种族主义暗流。