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下列属于初级资料搜集的方法有（ ）。
下列属于初级资料搜集的方法有（ ）。
How far do birds usually travel from their summer homes to t
How far do birds usually travel from their summer homes to their winter ones?
测量学按照作用范围分类，不包括（ ）。
测量学按照作用范围分类，不包括（ ）。
It's terribly hot in the office; we're going to have an air-
It's terribly hot in the office; we're going to have an air-conditioner ________
The article gives us a summary of the situation in the first
The article gives us a summary of the situation in the first part and then discu