be back中的back是什么词性？

Answer 1

be back 中的 back 的词性是副词。
back 是一个多词性单词（动、名、副和形容词）。当用于系表结构的句子中时，back 只是副词。back 作为副词使用时的基本词义是“回来”、“回归”的状态。例：
I'm back home now. （我现在回到家里了。）
They will be back in three weeks. （他们三周后回来。）

Answer 2

这里的“back”属于副词，表示“回来”的意思。

back
英 [bæk] 美 [bæk]
n.
背，背部;背面，反面;后面，后部;（椅子等的）靠背
vt.
使后退;支持;加背书于;下赌注于
vi.
后退;倒退
adj.
后面的;背部的;以前的;拖欠的
adv.
以前;向后地

例句：

The photographers drew back to let us view the body    

摄影师往后退开，好让我们查看尸体。 

I went back to bed      

我回到床上。 

The rail company said it expected services to get slowly back to normal      

铁路公司表示，其运输服务将慢慢恢复正常。 

She handed the knife back      

她递还刀子。 

They wrote back to me and they told me that I didn't have to do it      

他们回信告诉我说不必那么做。 

Can I come back to the question of policing once again?      

我能再回到维护治安的问题上来吗？ 

Short skirts are back      

短裙又流行起来了。 

Her hair was tied back      

她的头发扎了起来。 

She lay back and stared at the ceiling      

她躺下盯着天花板。 

Nick looked back over his shoulder and then stopped, frowning      

尼克回头看了看，又皱着眉头停了下来。 

Meanwhile, back in London, Palace Pictures was collapsing      

与此同时，伦敦的皇宫影业公司也正在分崩离析。 


He paced back and forth      

他来回踱步。 

Her son was lying peacefully on his back      

她儿子安静地仰面躺着。 

She raised her hands to the back of her neck      

她举起双手放于颈后。 

He opened the back door      

他打开了后门。 

There was a neatly folded pink sweater on the back of the chair.      

椅子的靠背上搭着一件叠得整整齐齐的粉色毛衫。  

Answer 3

back是形容词,形容回来的状态,不能在前面直接主语beback是动词,描述已经回来了,可以在前面直接加主语

Answer 4

副词

Answer 5

形容词