求教几个英语句子第一个 It was starvation quantities but the extreme lac

求教几个英语句子
第一个 It was starvation quantities but the extreme lack of water was the hardest to cope with.为什么这句It was后面没有not
第二A few varities,however,cankill humans,so it is just as well that snakes are very shy and usually attack only if they are disturbed and fell threatened.这句的so it is just as well that怎么解释