重点讲解：
1. used to do sth.
过去常常；过去曾做某事；
eg. We used to be good friends, but fell apart about a year ago.
我们过去曾经是好朋友，但一年前关系破裂了。
eg. Wood is often used to make desks and chairs.
木材常常被用来制作桌椅。
2. stand out
引人注目；显眼；突出；出色；
eg. He played the violin, and he stood out from all the other musicians...
他演奏了小提琴，把其他所有乐师都比了下去。
eg. His height makes him stand out in the crowd.
他身材高大，因此在人群中很突出。
3. over and over again
一再；再三；反复；
eg. I don't understand it,' he said, over and over again.
“我不明白，”他反复不停地说。
eg. The unknown word turned up over and over again in the text.
这个生词在文中反复出现。