【简答题】光栅常数为2um,缝宽为1um,总宽为6厘米的光栅,当光垂直入射于栅面时,要分辨500纳米和500.01纳米两条谱线,应选用第____级光谱
【判断题】在没有系统误差的前提条件下,总体平均值就是真实值
【单选题】--- I need to advertise for a roommate for next term. --- _____? Mary is interested.
【单选题】Why does the professor say this:
A.
She thinks that the spelling of the term is not important.
B.
She assumes that the students know how to spell the term.
C.
She knows that the term can be found in the textbook.
D.
She does not want to spend time explaining the term.
【判断题】在没有系统误差的前提下,总体平均值就是真实值。( )
【单选题】Man: Hurry, there is a bus coming. Woman: Why run? There will be another one in two or three minutes. Question: What does the woman mean?
A.
The next bus is coming soon.
B.
The bus will wait a few minutes at the stop.
C.
There are only two or three passengers waiting for the bus.
D.
They can catch this bus without running.
【单选题】某消费者需求曲线上的各点( )。
C.
对应的价格都是消费者购买相应的商品数量所愿意支付的价格