a block of flats a block为一栋,即为一栋楼房。 the roof of a block of flats the roof为房顶,即一栋楼房的房顶。 Once he landed on the roof of a block of flats and on another occasion, he landed in a deserted car park. once为曾经,有次。land为降落。on occasion为偶尔,有时。on another occasion为还有一次。deserted为荒废的。car park为停车场。 即整句翻译为:有次他降落在一栋楼房的房顶,还有一次他降落在一个荒废的停车场。