" What case is this" ? he asked in a deep voice, out of his broad bell mouth.

“这是什么案子”？他从他宽阔的喇叭口中用低沉的声音问道。

Only a mounded upper curve remained like half a bell mouth, the curve of a tunnel rearing above the dunes.

只剩下一个像半个喇叭口一样的丘状上部曲线，隧道的曲线在沙丘上方竖起。