secondary safety zone二级: two stage; two level; second ...安全: safe; secure; safety; securi ...区: H region; H二级安全阀: secondary safety valve二级安全壳: secondary containment下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:二级安全区，即可在微信中查询翻译
