小红在计算52×38后,又用38×52来验算,小红在这里运用了( )A.乘法交换律 B.乘法结合律C.乘法交换律和乘法结合律
_______ have you been in hospital, Frank?
Fourteen days.( )
How soon
How often
How long
Kate, don't forget to _______ the light when you leave the room.
OK, mom.( )
cut off
put off
turn off
Mum, _______ I do my homework tonight?
No, you _______. But you must finish it before Sunday.( )
need; mustn't
must;needn't
must;mustn't
Gift shop had been _______ when we got there.( )
close
to close
closed
He asked _______ Betty came home late last night.( )
weather
whether
where