明修栈道，暗度陈仓[míng xiū zhàn dào àn dù chén cāng]
词典pretend (to prepare) to advance along one path while secretly going along another
词典do one thing under cover of another：陈仓暗渡；明修栈道， 暗度陈仓；明修栈道，暗度陈仓；暗度陈仓。
1. 这时候，他们就开始明修栈道，暗度陈仓。
At the same time they are having an illicit affair.