1. This novel concerns peasant life after the reform.

2. She needn't concern herself with so much unimportant details.

3. They were all concerned with the matter.

以上三句都正确。解析如下：

句1，concern 是及物动词接宾语。意思是“涉及；关于”，等于 be about。是指小说“涉及或描写的内容”。此句的主语不能是“人”。

句2 和 句3，这是“相互变式”，都是表达主动意义。里面的奥秘可以参考以下内容：

be dressed in 或 be seated on ——缘何没有被动意义？

“被动语态表主动”，这是一个很有意思的话题，该现象的本质皆缘于反身动词跟反身代词的用法。主语和宾语同为一人，主语是动作的发出者，又是动作的接受者，这就出现了被动语态表示“主动” 含义的语言现象。例如：

John seated himself on the chair. = John was seated on the chair. 

The lady dressed herself in red. = The lady was dressed in red.

以上含有反身代词的例句，去掉 oneself 变成被动句，意思保持不变，仍表示主动含义。除了seat 和 dress 外，又如：

He committed himself to studying English.

= He was committed to studying English.

他致力于学英语。

He quickly accustomed himself to this new way of life.

=He was quickly accustomed to this new way of life.

他很快就习惯了这种新的生活方式。

You will have to accommodate yourself to the changed situation.

=You will have to be accommodated to the changed situation.

你必须适应变化了的形势。

She adapted herself to the new climate quickly.

=She was adapted to the new climate quickly.

她很快就适应了这种新气候。

He can't adjust himself to the whirl of modern life in this big city.

=He can't be adjusted to the whirl of modern life in this big city.

他无法适应这个大都市的现代生活的忙碌。

The old man addicted himself to smoking.

=The old man was addicted to smoking.

那位老人吸烟成瘾。

Nowadays some young people abandon themselves to drinking.

=Nowadays some young people are abandoned to drinking.

现如今，一些年轻人沉湎于饮酒。

You will have to bury yourself in your studies if you want to pass the exam.

=You will have to be buried in your studies if you want to pass the exam.

如果你想通过考试，就得专心致志地学习。

He hid himself in the woods.

= He was hidden in the woods.

他藏在森林中。

She should concern herself with your health.

= She should be concerned with your health.

她应关心你的身体。

After graduation he continued to devote himself to the research.

=After graduation he continued to be devoted to the research.

毕业之后他继续致力于研究工作。

He dedicated himself to the cause of science.

= He was dedicated to the cause of science.

他献身科学事业。