雨、水是液态,液态的特征是:没有一定的形状,但有一定的体积,密度最大;
水蒸气是气态,气态的特征是:没有一定的形状和体积,密度最小,且容易被压缩.
如图所示是某宾馆走廊廊灯的自动控制电路,走廊入口上方安装有反射式光电传感器,当人靠近到一定距离时,从光电传感器上发射的红外线经人体反射后被接收器接收,接收器中的光敏电阻R0阻值减小,定值电阻R两端的电压____,同时电磁铁磁性____,工作电路接通,灯泡发光,图中电磁铁的上端是____极.
下列有关分子、原子和离子的说法正确的是()
曲线y=xx-1x-2-3lnx在点1,0处的切线方程为( )
Would you like to learn English well?
4 weeks
Monday (18:30-20:00)
English Club
Phone NO.62258
Do you enjoy learning to use the computer?
3 weeks
Tuesday( 19:30-21:00)
Internet Club
Phone No.62279
Would you like to be an artist?
For drawing beginners only
8 weeks Thursday (19:00-20:30)
Art Club
Phone No.62537
Fancy taking photos?
Bring your camera with you!
6 weeks Saturday (9:00-10:30)
Photo Club
Phone No.62587
Are you good at swimming?
7 weeks
Sunday (100:00-11:30)
Swimming Club
Phone No.61852
Are you animal lovers?
5 weeks
Wednesday (14:00-15:30)
Nature Club
Phone No.61866
There are____clubs here for people to choose from.
People go to all these clubs____a week.
Only drawing____can go to Art Club.
____Club and____Club last for less than one month.
If you are free only in the afternoon, you can go to ____ Club.
People in Photo Club must bring a ____ with them.
If you like animals , you can call on ____
____ Club is the longest and ____Club is the second longest.
从离地面80m的高空中自由下落一个小球,求:自开始下落时计时,小球在最后1s内的位移是多少?(取g=10m/s2)