1.B (world第二次提到,加the,用where引导从句,where在从句中做地点状语
2.前半句指一般情况,用一般现在时,这里是把南方的一般天气情况（很少下这么大雪）和今年冬天发生过的情况对比.
3.因为时间是these few days所以用现在进行时,sell可以用主动语态表示被动含义,表示卖的如何,类似的有wash,如：This material washes easily.这个料子容易洗.
4.伴随状语是指状语从句的动作伴随主句发生,它的特点是：它所表达的动作或状态是伴随着句子谓语动词的动作而发生或存在的.
5.在句首的only如果后面跟了副词、介词短语或从句等状语,则主句用倒装结构.如only后跟的是主语,就不用倒装结构了.
Only when the war was over in 1918 was he able to get back to work．
Only in this way can you learn English well．
Only five men were hurt in the accident．（不倒装）