Hello, all. I have a question to ask. <br/><br/>I was using a sentence “~the goods will be shipped on week 39.”<br/><br/><br/><br/>However, someone told me that the correct way to say it was : "~in week 39", and that “on week ~“ did not exist grammatically.<br/><br/><br/><br/>Could you please tell me whether this is true and explain why?<br/><br/>Thank you in advance.