Human activities that have indirect effects on animals can be just as harmful.     1     当我们修建农场和工厂时, we destroy animal habitats and leave many animals with nowhere to live,     2     或者没有食物可吃.     3     We can also put animals in danger without ever entering their habitats. Air, water, noise and light pollution can all have a deep and damaging influence quite far from their source. Partly due to pollution caused by ship traffic and other human activities,     4     the dolphin population has dropped greatly. As the human population continues to grow,     5     so does the effect we have on animals.