—I’m losing my eyesight, I’m afraid.

—To finish this book, you ______ in front of your computer too long.

A．work

B．are working

C．have been working

D．worked

近代警察机关的建立及其体制和职权，均以宪法或法律为依据。古代警察执法极不严格，私刑普遍存在。 ( )