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? Even though not all sentences will be unclear with the omission ofwel the serial comma, its consistent use kan zijn a good habit. (See https://elliottp742oxf0.thenerdsblog.com/profile