中间等级

Scientists on Wednesday raised the alert level for Anak Krakatoa and Tangkuban Prahu -- which regularly spew gas and rumble -- from "normal" to "warning," the middle of three alert levels.

上周三，科将喀拉喀托火山和唐库班珀拉胡火山的警戒度由“正常”提高到“警告”，三警戒的中间等，因为这两座火山近来定期喷出火山灰，并发出隆隆的声音。