当赖兹纳稳定指数()时,水将严重结垢。
A、<7.5
B、>7.5
C、<0.6
D、<3.7
参考答案:D
选出句中的错误并改正。
( ) 1. I usually walks to school.
A B C
( ) 2. I'm going to playing the guitar.
( ) 3. I have much dresses.
( ) 4. I want singing a song.
( ) 5. Are you always do your homework?
网络安全的定义和目标是什么?