The first definition has no arguments, hence the empty square brackets.

第一个定义没有参数，因此方括号是空的。

youdao

There are no customers here. A winter wind hasreplaced what should have been the sound of merchants selling their wares, andsnow blankets the empty square and two blue temporary cabins.

没有顾客，冬日的风取代了本应有的商人兜售货物的叫卖声，积雪覆盖了空荡荡的广场和两个临时的蓝皮小棚屋。

youdao

Tap the square horizontally or vertically adjacent to the empty square to move the pieces till you get the original image.

点击空位四周的图块就可以将其移动到空位上，直至把整幅图片复原。

youdao

Essex-born Mark Wallinger is best known for his sculpture for the empty fourth plinth in Trafalgar Square.

BBC: Tracey Emin to appear at festival

He drove down an empty Piccadilly, crossed Trafalgar Square in silence, and parked outside the unguarded Buckingham Palace.

NEWYORKER: The Autobiography of J.G.B.

The work is presented on the empty Fourth Plinth of Trafalgar Square and is a wry response to a square that is dominated by a male, disabled figure.

BBC: NEWS | Programmes | Newsnight | Newsnight Review | Marc Quinn