The company had a new automobile engine that it was developing,but kept it a hush - hush project until they knew it was successful.
The company had a new automobile engine that it was developing,but kept it a hush - hush project until they knew it was successful.
该公司正在研制一种新的汽车引擎，但在没有成功之前一直不张扬这一秘密项目。