our teacher entered the room高分悬赏!!

这是一个独立主格结构，有介词in的话，不需要介词with，也不需要物主代词。

如果改成非独立结构，加上介词with，同时也要加上物主代词，变为：with a book in his hand.

下面有详解，你有时间就看看吧：
独立主格结构
非及物动词就是cry,smile,sleep简单说就是这类你一个人就可以完成的动作,所以没有必要用被动语态.你说"我哭了",总不能转变成"我被哭了"吧?
第一个问题说来话长,不知道下面这些材料能不能帮到你~
独立主格结构本身不是句子，在句子中作状语，表示时间、原因、条件、伴随等。常见的独立主格结构有如下几种：
1. 名词/主格代词+现在分词。名词/主格代词与现在分词之间主谓关系。如：
The girl staring at him (= As the girl stared at him), he didn”t know what to say. 姑娘两眼望着他，他不知道说什么好。
Time permitting (= If time permits), we will go for an outing tomorrow. 如果时间允许的话，我们明天去郊游。
2. 名词/主格代词+过去分词。名词/主格代词与过去分词之间的动宾关系。如：
The problems solved (= As the problems were solved), the quality has been improved. 随着问题的解决，质量已经提高了。
Her glasses broken (= Because her glasses were broken), she couldn”t see the words on the blackboard. 由于眼镜摔坏了，她看不见黑板上的字。
3. 名词/主格代词+不定式。名词/主格代词与不定式之间是主谓关系，且强调的是一次具体性的动作。如：
He is going to make a model plane, some old parts to help. 借助于一些旧零件，他要做一个飞机模型。
They said good-bye to each other, one to go home, the other to go to the bookstore. 他们道别后，一个回了家，一个去了书店。
4. 名词/主格代词+形容词。如：
An air accident happened to the plane, nobody alive. 那架飞机遭遇了空难，无一人生还。
So many people absent, the meeting had to be called off. 这么多人缺席，会议不得不取消。
5. 名词/主格代词+副词。如：
He put on his sweater wrong side out. 他把毛衣穿反了。
The meeting over, they all went home. 会议一结束，他们就都回家了。
6. 名词/主格代词+介词短语。如：
The boy goes to the classroom, book in hand. 那男孩手里拿着书去教室。
Mary was sitting near the fire, her back towards the door. 玛丽靠近火炉坐着，背对着门。

hand 先有in , 但是我觉得book 前有个with

老师进到房间，手里拿本书。是不用填冠词啊。

这是省略结构 （with a) book in (her/his)hand

our teacher entered the room,with a book in his hand.