alone可做副词可做形容词，在这里是副词，至于你追问他人的问题，我替他回答一下“leave+宾语+宾补”的用法
Leave+宾语+宾语补足语，其中宾语补足这一成分可以由过去分词、现在分词、形容词、副词、介词的复合结构等来充当，分述如下：
1．由过去分词来充当宾语补足语：leave sth/sb done，常用来表示宾语所处的状态或表示动作已经完成。
(1)Please excuse me if I have left any of your questions unanswered.
(2)He got up slowly leaving the lunch unfinished.
(3)Did you leave the doors and windows firmly fastened?
I can't leave such an important matter undone/unfinished. 我不能让这样一件重要的事半途而废。
The moving story left him unmoved. 他对这个令人激动的故事竟然无动于衷。
△可用于被动语态：
Hi！My patient can’t be left unattached.
2.由现在分词来充当宾语补足语：leave sb/sth doing,常用来表示使某人或某物一直做某事：
(1)Don’t leave her waiting outside in the rain.
(2)They went off together and left me sitting there.
(3)We left him painting the gate.
△可用于被动语态：
Now the temple has only its walls left standing.
The papers were left lying around.
3.由形容词来充当宾语补足语：
(1)You’d better leave the drawing-room door open.
(2)His illness has left him weak.
△可用于被动语态：
The window was left open.
4. 副词作宾语补足语
What has left him away for so long?什么事使他离开了这么长时间?
5. 由介词的复合结构充当宾语补足语：
(1)Leave him in peace!
(2)His illness left him with a weak heart.
(3)You’ve left her name off the list.
This matter left her without a way of hope. 这件事使她没有一丝一毫的希望。
△可用于被动语态：
I was left without a ray of hope.
6不定式相对比较少；例如 leave me here to bleed 让我在这受伤流血
其实只是把非谓语运用到leave里 没什么难得 单独用你会不会呢
例如 He put forward a very good suggestion at the meeting,making everyone surprised 这里make就做了非谓语 现在分词表示伴随
这是我第一次回答，能否给个最佳？
参考资料：网上找的