scrape v. 刮擦
I must have scraped some of the paint off when I was parking the car.
我准是停放汽车的时候刮掉了一些油漆。
He bent over to scrape some dirt off his shoes.
他弯腰刮掉鞋子上的尘土。

Harry found himself shaking hands with everyone in the Leaky Cauldron

find somebody/something doing something是固定用法
eg:Often he found her quietly weeping alone.
她意识到自己常常独自垂泪。

find oneself 后面可以接现在分词doing或过去分词done的形式，意思是：discover state of sb./sth.是突然意识到某人/某事处于某种状态。。现在分词表示主动含义；过去分词就是表示被动含义。例如：
Then I found myself surrounded by half a dozen boys.
然后我发现六个男孩围者自己。
Dick found himself walking in the direction of Mike's place.Dick
不知不觉的朝Mike的住处走去。

I'm all of a flutter

be all of a flutter 激动、紧张，不安，忐忑
Mother is all of a flutter because of thunder and lightning.
由于电闪雷鸣,妈妈感到十分不安。
flutter n./v. 摆动，鼓翼，烦扰
They unfurled the flag and let it flutter in the wind.
他们将旗展开让其迎风招展。
There was a flutter of wings among the trees.
树林里响起一阵飞鸟的拍翅声。