题目

In the forest or in the fields you can often see small hills of earth and busy little ants. Ants live in different 21. An ant has two strong jaws to22 soil, to cup up food, to 23 the eggs or the young.The head of an ant is triangular(三角形), with two eyes for 24 uses and sometimes three more very small 25, which are made up of many parts, 26 the ant can see 27 that moves around it. Some of these eyes see things near it; others can see things 28 in the distance.The ant has six legs. Its feelers have twelve joins(接合点), 29 which the ant finds its 30 in its underground home. Some ants do电解水生成的氢气和氧气的体积比是（　　）A．2：1B．1：2C．8：1D．1：8