Warning: file_put_contents(/www/wwwroot/ppbbu/4cd.cn/cache/a0d3b4879189718fa2c12e73a7006aa0.txt): failed to open stream: No space left on device in /www/wwwroot/ppbbu/4cd.cn/index.php on line 55 backward difference approximation是什么意思，backward difference approximation的翻译，backward difference approximation音标、读音、用法和例句_沉淀汉英词典