Therefore, test and verity investigate data's truth is this follow - up investigate's key.

因此, 验证调查数据是否真实可靠是这次追踪调查工作的关键.

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There are two methods for studying the growth level , the cross - sectional investigation and the long it.

在研究生长发育方面,有横剖面调查和纵向追踪调查两种方法.

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