1. They screw the shopkeeper down.
   他们逼着老板降价。
2. We sat down to rest under the shade of a tree.
   我们坐在树荫下休息。
3. The workers are laying down a keel.
   工人们正安龙骨。
4. Scraped my fingernails down the BlackBoard.
   用我的指甲在黑板上刮擦
5. Five girls in rank came stepping down the plank.
   5个姑娘一列踏着木板走下来。

　1个名词解释