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：back to square one”专题等有关资料，供考生参考!
back to square one
An expression used to mean that it is necessary to stop whatever one has done on a new project and to start again completely.
EXAMPLE:
When our experimental design for a new solar automobile failed totally on the first day of testing, our engineering department knew it was back to square one.