1 sentence

1. 他想要独自一人环球航行，这简直是异想天开。

   tā xiǎng yào dú​zì yī rén huán​qiú háng​xíng, zhèi jiǎn​zhí shì yì​xiǎng​tiān​kāi.

   His plan to sail around the world alone is simply a pipe dream.

   Source: Dong Chinese Dictionary