l didn't go to the cinema last night,for l -----(see) the fi

你好
填 had seen  已经看过 （过去完成时）
主句：l didn't go to the cinema last night 我昨晚没去看电影.（一般过去式）从句：for I had seen the film.  因为我看过那部电影了. （过去完成时）
很明显,从句发生在主句之前,主句是一般过去式,那么从句就是过去的过去,即：过去完成时.
所以填 had seen.
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