重点讲解：
1. pack up
打点（行装）；
eg. They packed up and went home.
他们打点行囊，回家了。
eg. He began packing up his things.
他开始收拾行李。
2. spread out
摊开；铺开；
eg. She spread a towel on the sand and lay on it.
她在沙滩上铺了一条毛巾，躺在上面。
eg. His coat was spread over the bed.
他的外套摊在床上。
3. chop down
砍倒；伐倒；
eg. Sometimes they have to chop down a tree for firewood.
他们有时只好砍树当柴烧。
eg. Every morning the old man went out to chop down trees.
每天一早，老人就去森林伐木。
