⑴ 当我们到达电影院时，电影已开始二十分钟了（翻译成英语）
翻译如下：
当我们到达电影院时，电影已开始二十分钟了
When we arrived at the cinema, the film had already been on for twenty minutes
⑵ 电影开始半个小时了英语四种翻译
The film has been on for half an hour.
The film has been on since half an hour ago .
The film began half an hour ago.
It's half an hour since the film began.
Half an hour has passed since the film began.