Because of the complexity of our modern machine, we need our workers ______.

A．It’s not healthy for the environment.
B．People only like to catch big fish.
C．There are too many small fish.
D．The smaller fish can get lost in the lake.

A．The Northern Pike will die.
B．The wells will be polluted.
C．Poisons will kill the Northern Pike.
D．The Northern Pike will swim into other lakes.