虎、狼等动物能生育幼仔，这种特征是（ ） A．生物能繁殖 B．生物能生长 C．生

Today’’s lecture we’’ll center on the prehistoric people of Nevada Desert. Now most of these prehistoric desert people (36)______the countryside throughout the year. You might think that they’’re wandering aimlessly. Far from it, they actually followed the (37)______of carefully planned moves. Where they moved depended on where food was (38)______. Places where plants were ripening or fish were (39)______. Now often when these people moved, they carried all their (40)______on their backs. But if the journey was long, extra food and tools were sometimes stored in caves or (41)______rocks. One of these caves is now an exciting (42)______ site. Beyond its small opening is a huge underground (43)______. Even though the cave is very large. It was certainly too dark and dusty for the travelers to (44)____________. But it was a great place to (45)____________. And tremendous amounts of food supplies and artifacts have been found there.The food includes dried fish, seeds and nuts. The artifacts include stone spear points and (46)____________. The spear points are actually rather small. Here is a picture of some that were found. You can see their size in relation to the hands holding them.

地球公转产生的地理现象有[ ]

A、太阳东升西落现象

B、昼夜更替现象

C、四季变化

D、一天24小时

该病人术后5天出现黑便，最可能的原因是

A．小弯侧关闭止血不确切

B．吻合口出血

C．吻合口部分粘膜坏死脱落

D．应激性溃疡

E．术后胃内残余血

 阅读下面的文字，根据要求作文。

自觉

一个官员因公出访德国。一天，他走过一个路口，指示灯显示的是红色。他就止步等待。同他一起等待的还有一位10多岁的德国男孩。他等待了10多分钟，路口的指示灯依然是红色，他意识到是灯坏了，于是他就走了过去。等他办完事回到那个路口时，他发现那位男孩还站在那儿。

上面的文字，引发了你怎样的联想或感悟？请根据你的联想或感悟写一篇文章，不少于800字。

分泌降钙素的细胞是（）。

A.小肠上部K细胞

B.甲状旁腺细胞

C.甲状腺C细胞

D.胰岛B细胞

E.胰岛A细胞