老年人钙的吸收率为()。
A.10%
B.20%
C.30%
D.40%
E.50%
参考答案:B
解析:老年人对钙的吸收利用能力下降,钙的吸收率一般在20%左右。
根据所给单词或汉语提示写出其正确形式(共10小题;每小题1分,满分10分)
1.The villagers _________(遭受)a lot after the flood.
2. Are you a visitor or a (native) here?
3. (gradual),their marriage got better.
4.Your friend comes to school very ________(心烦意乱的).
5.I said hello to her, but she _________(不理睬)me completely.
6.This new library was (official) opened last week.
7. I (recognize) that I had made a mistake.
8.Our parents are always _______(关心)about our study and health all the time.
9. It was quite terrible. It took me some time to _________(使镇静)down myself.
10. The army is under the king’s direct (command)
如图中是我们学过的五种动物,请据图回答有关问题:
(1)A是一种会飞的动物,它的身体可分为______、______、______三部分,胸部有______对足______.
(2)B生活在水中,它的胸鳍和腹鳍的功能是______,控制前进方向的是______.
(3)C是国家二级保护动物,俗称娃娃鱼,属于______动物.
(4)D是一种珍稀动物,其有一种独特的呼吸方式与其体内结构--______有关.
(5)E与D相比,E在生殖发育方面的特点是______.
(6)上述类群中属于无脊椎动物的是______;属于恒温动物的有______和______;上述动物中学习能力最强的是______.(填字母)