一、He had a shrewd suspicion that Dumbledore might have stepped in to stop Snape failing him on purpose.

1.结构分析

本句是同位语从句，从句部分“Dumbledore might have … on purpose.”是对“suspicion”内容的解释。

2.重点语法

stop sb (from) doing sth 阻止某人做某事

类似表达还有：

prevent sb (from) doing

keep sb from doing sth(此处from不可省略,否则意义相反)

3.重点词汇词组

shrewd 判断得准的，高明的

eg：I have a shrewd idea who the mystery caller was.

这个神秘的来访者是谁，我能猜个八九不离十。

step in 介入，插手干预

eg：If no agreement was reached, the army would step in.

如果达不成协议，军队将会干预。

on purpose 故意地，成心地

eg：To be seen crying sadly, the little boy raised his head and had the tears falling down on purpose.

为了让别人看见他哭得很伤心，小男孩抬起了头故意让眼泪掉下来。

二、Harry wouldn't have thought it possible that Snape's dislike for him could increase, but it certainly had.

1.结构分析

本句是宾语从句，其中it是形式宾语，真正的宾语是that引导的“Snape's dislike … had”这句话。

2.重点语法

dislike for sb 不喜欢某人

【拓展】dislike的用法

①用作名词时

have a dislike to doing sth

have a dislike for/of sb

take a dislike to sb

②用作动词时

dislike sth

dislike doing sth

三、A muscle twitched unpleasantly at the corner of Snape's thin mouth every time he looked at Harry, and he was constantly flexing his fingers, as though itching to place them around Harry's throat.

1.结构分析

本句是由and连接的两个句子。

2.重点语法

itch to do sth 渴望做某事,恨不得

eg：My fingers itch to box his ears.

我手痒了，想给他一个耳光。

3.重点词汇词组

twitch v/n痉挛，抽搐

eg(v)：Her lips twitched with amusement.

她忍俊不禁地颤动着嘴唇。

eg(n)：She has a twitch in her left eye.

她左眼跳了一下。

flex 屈伸,活动(四肢或肌肉,尤指为准备体力活动)

eg：He slowly flexed his muscles and tried to stand.

他缓慢地活动了一下肌肉，想站起来。

as though 好像

eg：She smiled, as though solaced by the memory.

她笑了，仿佛在往事的回忆中得到了安慰。

【拓展】as though 和 as if的主要区别

as if从句可以使用省略语法，但as though不能.

eg：He sat there quietly as if (he was/were) sleeping.

他静静地坐在那里，好像睡着了。

四、This meant that the end of term feast took place amid decorations of scarlet and gold, and that the Gryffindor table was the noisiest of the lot, as everybody celebrated.

1.结构分析

本句结构为：主语+谓语+两个that引导的宾语从句

2.重点词汇词组

scarlet 猩红的

eg：She went scarlet with embarrassment.

她窘得满脸通红。