What were you thinking about so hard that you didn't notice me coming? 用中文 (繁體，臺灣) 要怎麼說？

你剛在想什麼想得這麼認真，連我來了都沒注意到？,你剛在幹嘛？這麼用功？我來了你都沒注意到,你剛在想什麼想得這麼認真，連我來了都沒注意到？