- 비말은 비오일성(기름입자가 아님)이므�? 오일 성분�?차단능력은 크게 중요하지 않다. If a grammatical basic principle that is definitely additional to 서툴�?is actually a vowel �?and there is no other possibility in addition to a vowel �?then that grammatical theory cannot be extra to 서툴�?