New Words：
string [striŋ]
n.线；一连串
v.悬挂；系；扎；把…连在一起
strung [strʌŋ] 动词string的过去式与过去分词
Sample Sentences：
The key is hanging on a string by the door.
She wore a string of pearls around her neck.
A string of accidents happened at that corner.
These girls are stringing pearls.
Flags had been strung up across the street.
pearl [pɜːl] n. 珍珠
New Words：
mower ['məuə] n. 割草机
Sample Sentences：
The mower is covered with rust.
Do not lift the mower if the engine is running.
I borrowed a mower from my neighbor to cut grass in my garden.
New Words：
drag [dræg] v.拖；拉；生拉硬拽
Sample Sentences：
He grabbed her and dragged her away.
He dragged the heavy chest across the floor.
The bottom of her long dress dragged in the dust.
She dragged herself out of bed, still half asleep.
New Words：
exchange [iks'tʃeindʒ]
n.交换；交流；交易所；兑换
v.交换；交流；交易；兑换
in exchange for 作为……的交换
Sample Sentences：
Would you like my old TV in exchange for this camera?
I buy you lunch and you fix my computer. Is that a fair exchange?
I'd like to exchange some pounds for dollars.
Everyone in the group exchanged email addresses.
We exchanged our opinions about the accident at the meeting.
New Words：
swap [swɔp]
v.换；掉换；交换；替换
n.〈非正式〉交换；〈非正式〉交换物
Sample Sentences：
I'll swap you three of mine for one of yours.
I liked her coat and she liked mine, so we swapped.
As you like my dress and I like yours, shall we do a swap?
Let's do a swap . You work Friday night and I'll do Saturday.