Southbank, at an eastern bend in the Thames, is the center of British skateboarding, where the continuous crashing of skateboards left your head ringing. I loved it. I soon made friends with the local skaters. We spoke our own language. And my favorite: Safe. Safe meant cool. It meant hello. It meant don’t worry about it. Once, when trying a certain trick on the beam (横杆), I fell onto the stones, damaging a nerve in my hand, and Toby came over, helping me up: Safe, man. Safe. A few minutes later, when I landed the trick, my friends beat their boards loud, shouting: “Safe! Safe! Safe!” And that’s what mattered—landing tricks, being a good skater.

上面一段摘自2021年高考的全国甲卷（全国2卷）的阅读理解C。请问最后一句中的独立动名词 landing tricks, being a good skater 是什么用法？作什么成分？

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