In Australia, there are only three species of mammals that lay eggs in the world.The most famous is the ______.
A、platypus
B、koala
C、wombat
D、wallaby
【正确答案】：A
【题目解析】：There are only three species of mammals that lay eggs in the world. Australia is the home of all three. The most famous is the platypus.参见教材P87.
