Hi,<br/><br/>What's the difference between<br/><br/>-"I'll come to Germany not at a weekend, but on a weekday" and "I won't come to Germany at a weekend, but on a weekday";<br/><br/>- "He is good not only at math, but also at history" and "He isn't good only at math, but also at history"?<br/><br/>Thanks in advance.