边长为L的正方形金属框在水平恒力F作用下运动,穿过方向如图的有界匀强磁场区域.磁场区域的宽度为d(d>L)。已知ab边进入磁场时,线框的加速度恰好为零.则线框进入磁场的过程和从磁场另一侧穿出的过程相比较,有
How long have you had the cellphone, Kang kang?
I've had it two months.It helps me a lot.( )
for
since
in
on
Are there any notebooks on COVID﹣19(新冠肺炎病毒) in your school?
,They tell us how to protect ourselves in this big event.( )
Yes, they are
Yes, there are
Yes, there is
Yes, it is
To keep our city clean and beautiful the are always very busy in the street.
They should be respected by all the people.( )
drivers
postmen
firemen
cleaners
Your handwriting is beautiful.
Thank you, I write than before( )
careful
more careful
more carefully
carefully
Maria, how do you like Journey to the west, one of the four classic novels of Chinese literature?
Wonderful! I like___very much.( )
one
them
it
its