A. vi. 下落 It will be cooler when the sun has set.
B. vt.(1)放置；摆设 She set the dish on the table.  
 Let’s set the clock by the radio signal.
(2)规定；确定 He set a strict rule for himself.
 Have they set the time for the meeting?
(3)使某人做事或处在某种状态
 With only a few words he set us laughing.
 What he said set me thinking.
 He set all the prisoners free.
 That set all our doubts at rest.这消除了我们所有的怀疑。
C.习语
set about doing sth.= set out to do sth.开始做
set an example做出榜样
set…apart拨出；留出
  A room has been set apart for the purpose.
set…aside拨出；积蓄；不理会
set…back往回拨；使倒退
set…down放下；写下；制定
set fire to sth.= set sth. on fire放火烧
set foot in…进入；踏上
set…forth列举；提出；动身；起程
set…in order整顿
set…loose释放；解开
set off动身
set…off燃放（鞭炮、烟花等）；引起
set one’s mind/ heart on…下定决心
set out动身；出发
set…out列举
 He set out his reasons for what he had done.
set sail启航
set… to work使开始工作
 He set to work at once writing the book.
 He set everyone to work together.
set…up立起来；成立；修建
set…upside down颠倒过来