sound signals in restricted visibility能见度: visibility; conspicurity; se ...不良: bad; harmful; undesirable; u ...时: shí]使用: make use of; use; employ; ap ...的: 4次方是 The fourth power of 2 i ...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:能见度不良时使用的声号，即可在微信中查询翻译
