Objective:To understand pupil s vision low rate in the city and countryside and it s influencing factor.Method: Using stratified cluster sampling,sampling an elementary school respectively in the city and countryside,carries on the check by sight and the correlation factor investigation.Result: The city pupil s prevalence rate is higher than the countryside s,the vision low concerns with the outdoor activity and accessing the net custom.Conclusion: The vision low correlates closely with the short distance w...
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He delighted in sampling an array of them, telling the waiter: "Just bring a couple of spoons, and I'll have a little of everyone's."
他开心地把一排甜品一个挨一个地品尝了一遍,并且对服务员说,“拿两个勺子来,我要尝尝每个人的甜品。”
Method: Using stratified cluster sampling, sampling an elementary school respectively in the city and countryside, carries on the check by sight and the correlation factor investigation.
方法:应用分层整群抽样方法,在城市、农村小学中各抽取一所小学,进行视力检查及相关因素调查。
First, through a pine forest, spurning the mule trail and the shortcuts, and sampling the blueberries; then through an alluvial cone, wasting precious energy.
首先,穿过一片松树林,没在意骡子走过的足迹和捷径,品尝着蓝莓;然后穿过冲击堆,浪费了宝贵的精力。
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