Sally __________ her homework in the evening.
A:doesn't
B:doesn't do
C:don't
D:don't do
已知 是方程x-ky=1的解,那么k=____.
在紧急情况下,蜥蜴的尾巴能自动断落以逃避敌害.蜥蜴的这种行为是( )
如图为探究通电直导线周围磁场分布的实验。实验时先在有机玻璃板上均匀地撒上铁屑,然后给直导线通电,