Difficulties
n. 困难( difficulty的名词复数 ); 难度; 难事; 麻烦
🗣️ 情景例句
It's for a book.
是为一本书拍的。
He likes playing at the model buiding.
他喜欢玩摸型建筑。
The further off this solid obstruction, the longer time will elapse for the return of the echo.
固体障碍物越远。回声返回所用时间就越长。