Open-air means it happens outside, with the sky above you, not in a hall. An open-air concert, an open-air market, an open-air pool, an open-air film in summer.

Open-air means意思是 it happens outside事情在外面發生， with the sky above you頭上就是天空， not in a hall不是在室內的廳裡。 An open-air concert露天音樂會、 an open-air market露天市場、 an open-air pool露天泳池、 in summer夏天的 an open-air film露天電影。

People still often write the little line in the middle. It feels a bit more like a named kind of place than just saying outdoor: “open-air theatre” is a type of theatre.

People人們 still often還是常常 in the middle在中間 write寫上 the little line那條小線。 It它 than just saying outdoor比起只說 outdoor， feels a bit more like更有一點 a named kind of place「有名字的一類場所」的感覺： “open-air theatre” is是 a type of theatre一種劇場。

If it rains, the open-air plan is in trouble — that is the whole point of the word. In cities, shops also use it to sell a holiday feeling, even when you are only in a yard with lights.

If it rains如果下雨， the open-air plan露天的計畫 is in trouble就麻煩了—— that is the whole point of the word這正是這個字的重點。 In cities在城市裡， shops店家 also use it也拿它 to sell來賣 a holiday feeling一種度假的感覺， even when即使 you你 only只是 in a yard with lights待在一個掛了燈的院子裡。

You can say the concert is in the open air, with a space and no little line; the hyphenated form is the one that sits in front of a noun.

You can say你可以說 the concert音樂會 is in the open air在露天舉行—— with a space中間空一格、 and no little line不加小線； the hyphenated form帶連字號的寫法 is the one才是 that sits in front of a noun放在名詞前面的那一個。