English Skills 10th Edition by John Langan, Zoe Albright

تمرين 21

Underline the conclusion signal in the following paragraph.
A hundred years ago, miners used to bring caged canaries down into the mines with them to act as warning signals. If the bird died, the miners knew that the oxygen was running out. The smaller animal would be affected much more quickly than the miners. In the same way, animals are acting as warning signals to us today. Baby birds die before they can hatch because pesticides in the environment cause the adults to lay eggs with paper-thin shells. Fish die when lakes are contaminated with acid rain or poisonous mercury. The dangers in our environment will eventually affect all life on earth, including humans. Therefore, we must pay attention to these early warning signals. If we don't, we will be as foolish as a miner who ignored a dead canary-and we will die.