【正确答案】：
BOTH ROOM AND BEAUTY ARE NOUNS, BUT ROOM IN SENTENCE A IS USED AS A VERB WITHOUT CHANGING THE FORM, WHILE BEAUTY CANNNOT BE USED AS A VERB WITHOUT ADDDING AN AFFIX AS IN SENTENCE B. SENTENCE A IS A CASE OF CONVERSION, OR ZERO-DERIVATION WHEREAS SENTENCES B IS ONE OF SUFFIXATION AS THE SUFFIX -IFY IS ADDED TO MAKE BEAUTY A VERB. 
【题目解析】：房间和美丽都是名词，但是句子A中的房间用作动词而不改变形式，而句子B中的美丽不能用作动词，故添加词缀。句子A是转换或零派生的情况，而句子B是后缀法，因为后缀-ify被添加以使“beauty”成为动词。