白雪皑皑，在晚霞的映照下，呈现出一片红色，但是我们对雪地的知觉仍然是白色。这是因为人

在ΔABC中，AB=12㎝，BC=18㎝，AC=24㎝，ΔABC∽ΔA'B'C'，且ΔA'B'C'的周长为81㎝，求ΔA'B'C'的各边的长。

短文改错（共10分，每小题1分，满分10分）

One day a child was playing with a vase in great value. He careless put his hand into it. Hard as he tried, he could not pull it out. His father tried his best, too, but their efforts were in a vain. They were thinking of breaking the vase whenever the father said,“now , my son, why have one more try? open your hand or hold your fingers straight as you saw I doing, and then pull.”to his surprise, the child says, “I can’t hold my fingers straight like that, because I don’t want to drop my penny.” Thousand of us sometimes are so busy hold on to the world’s worthless penny that we cannot achieve liberation.

筛查新生儿先天性甲状腺功能减低症最常用的方法是()

A．血清T、TSH测定

B．干血滴纸片测定TSH

C．放射性核素检查

D．TRH刺激试验

E．骨龄测定

引起动机的主要因素有：（）

钢板越薄矫直辊颈应（）。