脚步犯规发球时踩线或双脚离地脚步违例发球时踩线或打球时脚过中线
Foot violation: stepping on the line when serving or leaving both feet off the ground. Foot violation: stepping on the line when serving or crossing the center line while playing
以上为机器翻译结果，长、整句建议使用 人工翻译 。
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