I must stress that goods were strictly¹ inspected before shipment with your representative on the spot.
我必须强调，货物装船前经过严格检验，而且你方代表也在场。

Let me emphasize how necessary it is to abide² by the contract.
我要强调，遵守合约是十分必要的。

I can't stress enough the disastrous³ consequences of breach⁴ of contract.、
我必须强调，违约会带来严重后果。

I must call your attention to the distinction between these two samples.
我要提请您注意两个样品之间的差异。

单词解析：
inspected；abide by；consequences这三个词（组）在商务谈判中，尤其是涉及到商务合同的时候都是非常实用的。inspect通常是指对货物的检验；abide by是指对合约，合同的遵守；consequence通常是指出现某种情况的后果。