see off的用法

see off的用法：
I went to the station to SEE them OFF.
I went to the airport to SEE them OFF.
我到车站/我到机场 送别 他们。
（常说的送人接人，see off是送人-- 看。。。离去）

A cat came into the back garden but the dog soon SAW it OFF.
猫进了后院（花园），狗很快就把它赶走。
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set off的用法：
The smoke SET the fire alarm OFF.
烟雾使火警报警器响起。
We SET OFF for work at seven-thirty.
我们7点半离开（家），（然后走路或开车或乘车)去上班。

The company SET OFF its overseas debts against it profits at home.
（。。。偿还它的海外债务。。。。）
Terrorists SET OFF a car bomb in the city centre last night.
Fortunately, no-one was hurt or killed.
（。。。引爆。。。）