答案：C

题目分析: lead 的逻辑主语是the boy ,with the boy leading构成独立主格结构，表伴随。

have difficulty (in)doing 在做…有困难，固定句型。句意：在那个男孩的带领下，我们毫不费力地找到了那个木桩。

点评：with 构成的短语是高考常考点。平时需记牢并理解独立主格结构的概念。固定句型平时多积累。with用法如下：介词with或without+复合结构，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下：

1. with或without-名词/代词+形容词；

2. with或without-名词/代词+副词；

3. with或without-名词/代词+介词短语；

4. with或without-名词/代词 +动词不定式；

5. with或without-名词/代词 +分词。

下面分别举例：

1、 She came into the room，with her nose red because of cold.（with+名词+形容词，作伴随状语）

2、 With the meal over ， we all went home.（with+名词+副词，作时间状语）

3、The master was walking up and down with the ruler under his arm。（with+名词+介词短语，作伴随状语。） The teacher entered the classroom with a book in his hand.

4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.（with+名词+不定式，作伴随状语） He could not finish it without me to help him.（without+代词 +不定式，作条件状语）

5、She fell asleep with the light burning.（with+名词+现在分词，作伴随状语） Without anything left in the cupboard， she went out to get something to eat.（without+代词+过去分词，作为原因状语）