与此相反，30到59岁之间的司机在载有乘客时出车祸的几率随着乘客的增多而减小。
点睛本句的主干是the risk of death decreases。between 30 and 59修饰drivers；with引导伴随状语。
by contrast意为“相反”，相当于in contrast。如：
The coastal areas have mild winters, but by contrast the central plains become extremely cold. 沿海地区的冬天天气暖和，而与此相反，中部平原却会异常寒冷。
考点归纳by contrast与in contrast含义相同，都表示“相反，大不相同”。与此含义相同的短语或者词汇还有on the contrary, conversely和oppositely，它们的区别在于：
by contrast与in contrast都只强调所比较的事物是不同的。如：
But, in contrast, it is only in modern times that Galileo has become a problem child for historians of science. 但是相比之下，对于科学史学家来说，伽利略唯有在现代才被看做是问题小孩。
on the contrary多用于观点或想法，暗示有很多不同方面的选择。如：
He is not poor, on the contrary, he is a millionaire. 他不穷，相反，他是个百万富翁。
conversely暗示所比较的两者截然相反。如：
Describe your greatest accomplishment and why it is important to you and conversely, your greatest disappointment and what you learned from that experience. 描写你最大的成就，并说明对你而言它为何重要，还要描写与此相反的你最大的失败经历以及从中得到的教训。
oppositely暗示所比较的两者之间矛盾突出而尖锐。如：
My plan for career is not single, oppositely, I tend to expand my work into diversification. 我的职业规划不是单一的，相反，我倾向于在不同的领域中开拓事业。