化学符号
____
2SO2
符号的意义
3个氮原子
1个钠离子
⑴When do you eat breakfast?____ A.It's warm and sunny.
⑵Can you make a snowman now?____ B.No,it isn't.
⑶What's the weather like today?____ C.I eat breakfast at 7: 15.
⑷What would you like to do?____ D.No,I can't.
⑸Is it windy and cold?____ E.I would like to go swimming.
下列不是修建青藏铁路需要解决的难题是( )
按拼音写汉字。
bào yǔ
shùn jiān
bào nù
如图所示的滑轮(不计摩檫),把重150N的物体匀速提起,所用拉力为100N,则关于该滑轮的说法中错误的是( )