•The report shows that drugs have penetrated every stratum of American society.报告显示，毒品已经渗入美国社会的各个阶层。

•The cliffs are characterized by remarkable zigzagging strata of shale, limestone and sandstone.悬崖的特征是，它们由一层层清晰易辨的页岩、石灰岩和砂岩交错构成。