一个由小菱形组成的装饰链,断去了一部分,剩下部分如图所示,则断去部分的小菱形的个数可能是(   )

用数学归纳法证明不等式 $\frac{1}{n+1}$ + $\frac{1}{n+2}$ +…+ $\frac{1}{3n+1}$ ≥ $\frac{25}{24}$ 对一切正整数n都成立．

选词填写    Thomas Edison was a great American inventor（发明家）. When he was a child, he was always ____ questions and trying out new ideas. No matter how hard it was, he never gave up.
    Young Tom was in school for only three months. His teacher didn't understand why he had ____ many strange questions. Most of them were not about his lessons. The teacher didn't want to teach Tom any ____ . He asked Tom's mother to take the boy home. Tom's mother____ him to read and write, and she found him be a very good pupil. He learnt very fast and became very ____ in science.

人体内氧浓度最高的部位是（　　）

给划线字选择正确的解释。

①纵横交错 ____

A.不正确,不对,与实际不符。B.差,坏。C.交叉着。

②浸没____

A.逐渐。B.泡,使浸透。

③吞天沃日____

A. 土地肥。B.灌溉,浇。