精品学习网考试频道小编应广大考生的需要，特为参加考试的考生策划了“PETS4写作精选短语：bread and butter”专题等有关资料，供考生参考!
bread and butter
(noun)
the primary or leading means of financial support, existence, or survival
EXAMPLE:
Bicycle manufacturing provides the company's bread and butter.