讨论：微生物（包括动、植物）可以生产我们所需的一切产品，但是涉及到工业化生产，对于某一种特定的产品，为何只有特定的微生物才具有大量表达的潜力？

—You'd better () work too hard like this.
—I see. You mean () too hard makes one tired and ill.

A．not; work

B．don't; working

C．don't; to work

D．not; working