A:b⩽ac
B:b2⩾ac
C:a2⩽b2⩽c2
D:b⩽a+c2
为了使教室内的学生上课免受周围环境噪声干扰,下面哪个方法有效合理()
A
Lost:A pencil box
It is blue.My name is Jenny Brown.My phone number is 236-9878.
Found:A watch
Is this your watch?Please call Dave. Phone number :236-8567.
Tina,
A nice black bag is in the school library .Is it yours? Ask Miss Li for it.---Jack.
A nice green notebook is in Classroom 2B.A photo of a girl is in it.Is it yours?E-mail me at Gina23@163.com.
在煮饺子的过程中,可观察到如下现象:饺子刚放入时,沉在水底;煮一段时间后,就浮了起来.你能试着解释这些现象吗?