The room was dark, so she asked me to _________ the lights.
A:turn up
B:turn down
C:turn off
D:turn on
如图,∠BAC=∠CDB=90°,请你从下列条件中任选一个,使得△BAC≌△CDA,并证明.①AB=CD;②AC=DB;③∠ABC=∠DCB;④∠ACB=∠DBC.
关于功率,下列说法中正确的是( )