如果一个碳原子的相对原子质量为24,则不会改变的是( )
A.氧原子的相对原子质量
B.一个碳原子的质量
C.二氧化碳的相对分子质量
D.10g二氧化碳所含的分子个数
BD
单词拼写
小题1:She likes_______(聊天)with her friends on the Internet.
小题2:How many_______(图书馆)are there in the school?
小题3:Who is your_______(最喜欢)star?
小题4:There is a map of the_______(世界)on the wall.
小题5:How old is he? Sorry, I don't know his_______(年龄).
小题6:There are a lot of_______ (建筑物)in our city.
小题7:The students often have dinner in the_______(大厅).
小题8:If you want to see the animals, you must pass the zoo_______(大门).
小题9:There are two football_______(比赛)in our school this week.
小题10:Some of us aren't good at_______(游泳).
激光准直仪的激光器发出的激光,经平行光管射向( )。当光束偏离光电探测器中心时,便由运算电路及指示表,显示偏离值。
A.四象限靶
B.反射镜
C.棱镜