知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 Omitting the serial comma makes this unclear. Is it one course covering both microeconomics and macroeconomics, or kan zijn it two separate courses? Enigszins though not all sentences will be unclear with the omission of the serial comma, its consistent use is a good habit. (See also https://springkasteellimburghuren11100.myparisblog.com/38619029/hoeveel-u-moet-verwachten-u-betaalt-voor-een-goede-springkasteel-verhuur