A:划线→锯割→钻孔→攻丝
B:划线→钻孔→攻丝→锯割
C:锯割→钻孔→划线→攻丝
D:划线→攻丝→锯割→钻孔
Jane ____ (cross) the bridge to school every day.
下列四种调查:①了解一批炮弹的命中精度;②调查全国中学生的上网情况;③审查某文章中的错别字;④考查某种农作物的长势.其中适合做抽样调查的个数有
=75-30
=45