The people are just about to blow out the candles at Lei Mei's birthday party when there is a knock on the door.

Dialogue One

duì bù qǐ wǒ  lái wǎn le
对  不 起,我  来  晚  了。
Sorry. I'm late.
wā wǒ  yǐ wéi nǐ bú huì lái le
哇! 我  以 为  你 不  会 来 了!
Oh, I thought you wouldn't come.
wǒ xiǎng gěi nǐ  yí  gè jīng  xǐ
我  想  给 你 一 个  惊  喜。
I want to give you a surprise.
zì  xíng  chē wǒ tài xǐ huan le
自  行  车! 我  太 喜  欢  了!
A bicycle! Thank you!
Dialogue Two
duì bù qǐ duì bù qǐ wǒ bú shì gù  yì de
对  不 起,对  不 起,我  不 是  故 意 的。
Sorry, I didn't do that on purpose.
méi guān  xi
没  关  系。
No worries.
kuài cā ca ba
快  擦 擦 吧!
Clear it quickly!
hǎo  de  xiè xie
好  的, 谢  谢。
OK. Thanks.

Explanation of difficult points

1. 以为
"以为" (yǐ wéi) means "to be under the impression that...". For example: "我以为是他呢,没想到是你。" (wǒ yǐ wéi shì tā ne méi xiǎng dào shì nǐ) which means "I thought it was him, I didn't realise it was you."

2. 惊喜
"惊喜" (jīng xǐ) always describes a good surprise.

3. 擦擦
"擦擦" (cā ca) is an example of the habit of duplicating verbs to denote short duration or casualness. It has the same effect as saying "擦一下" (cā yí xià), as covered in Lesson 16; another way to say it is "擦一擦" (cā yi cā). The second character in a duplicating verb is always pronounced with a lighter tone.