求帮忙翻译一下，逻辑大全TestC 12 - ChaseDream

Monarchbutterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes atleast three generations of monarchs to make the journey, so thegreat-great-grandchildren who finally arrive in the Mexican forests have neverbeen there before. Yet they return to the same trees their forebears left.Scientists theorize that monarchs, like homing pigeons, map their routesaccording to the earth’s electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install alow-voltage transmitter inside one grove of “butterfly trees” in the Mexicanforests. If the butterflies are either especially attracted to the grove withthe transmitter or especially repelled by it, lepidopterists will have evidencethat______