畜牧场有奶牛250头，奶牛头数是肉牛头数的25，畜牧场有肉牛多少头？

The Intergovernmental Panel on Climate Change (IPCC) was set up in 1988 to assess information on climate change and its impact. Its Third Assessment Report predicts global temperature rises by 2100 of between 1.4°C and 5.8°C. Although the issue of the changing climate is very complex and some changes are uncertain, temperature rises are expected to affect countries throughout the world and have a knock-on effect with sea-level rises.Scientists have argued about whether temperature rises are due to human activities or due to natural changes in our environment. The IPCC announced in 2001 that "most of the warming observed over the last 50 years is likely to be attributable to human activities". This was a more forceful statement than in 1996 when the Second Assessment Report stated that there was a "discernible human influence on the climate" which was the first time they had concluded such a link. Many experts believe the faster the climate changes, the greater the risk will be.Key points of the projections for climate change globally include that by the second half of the 21st century, wintertime rainfall in the northern mid to high latitudes and Antarctica will rise, that meanwhile Australia, Central America and southern Africa are likely to see decreases in autumn precipitation, that some land areas in the tropics will see more rainfall, and that there will generally be more hot days over land areas.

Based on the text, we know that temperature rises will probably________.

A．knock off sea levels

B．have a serious effect on sea-level rises

C．keep the sea level rising

D．keep knocking at the sea

消化性溃疡病人出现全腹压痛、反跳痛及板样强直，表明有（）

A.食管静脉破裂

B.癌变

C.穿孔

D.幽门梗阻

E.出血

如图是化学实验中常用到的部分仪器和装置．

（1）指出下列编号的仪器名称：a______、f______；

（2）过滤应使用的玻璃仪器有（写仪器名称）______、______、______；

（3）图A实验操作的目的是______，从该图观察到的实验现象中，你能得出的结论是______；

（4）实验室欲利用上述仪器完成高锰酸钾制氧气的实验，还需补充的仪器是______．

一只标有“12V  6W”的灯泡L与滑动变阻器R串联后接到电压不变的电源上，在R的阻值由最小变到最大的过程中，灯泡L的功率由6瓦变到1.5瓦，设灯丝电阻不随温度变化，则灯泡L的电阻为______欧；滑动变阻器R的最大阻值为______欧．

经典之所以为经典，就是因为它不但历久弥新，而且常读常新。常言道，“读书百遍其义自见”，苏轼也说“故书不厌百回读，熟读深思子自知”。经典之书，不同年龄读有不同年龄的体会，不同境遇读有不同境遇的领悟。小时候背诵经典，可能还不能领会其中要旨，但是背熟了，就成为一个人知识积累的一部分，长大后在生活和工作中自然会慢慢领会其中的精髓。这就是所谓“熟读而后能悟，悟而后能用，用而后生巧，巧而后出新”的道理。
这段文字主要谈论的是( )。

A．经典何以为经典
B．经典能常读常新
C．经典阅读具有阶段性
D．经典的精髓需慢慢领会