本章中，我们将重点对小型和中型的 C a t a l y s t交换机加以讨论，这些交换机的型号一般都 小于Catalyst 5000。其中，Catalyst 1900是型号最小的交换机，而且，就交换机每个端口的价 格来说，它也是最便宜的交换机。 Catalyst 2820比Catalyst 1900稍微大一点，它的带宽也比前 者宽一些

一、AD、DA的实际需求 二、D/A转换 三、A/D转换

Directions: In this section you will hear ten short conversations At the end of each conversation, a question will be asked about what was said. Both the conversation and the question will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A), B), C)and D), and decide which is the best answer. Then mark the corresponding letter on the answer sheet with a single line through

一.糖酶与消化: a-淀粉酶:唾液淀粉酶(水解a-1,4-糖苷键) 淀粉酶 胰淀粉酶 (a-d-g)n-淀粉酶:水解G非还原端(大麦麦芽) 支链淀粉酶:水解a-1,6-糖苷键 多糖酶纤维素酶(B-D-G)n:除牛等动物外,一般动物无此酶

一、无穷小(Infinitesimal) 分limf(x)-|=0 lim[(x)-A]=0 lima(x)=0 a(x)= f(x)-A 即,每一个有极限的函数f(x)都与一个趋于0的函数f(x)-A联系着。 因此,以0为极限的函数在极限理论和极限的计算中扮演着特殊而重要的角色

Junction potentials Whenever we change electrolyte or solvent there is a cost in that we create a double layer (electrode)which has a small but often measureable potential We call this potential a junction potential

Nobel lecture december 12, 1933 On passing through an optical instrument, such as a telescope or a camera lens, a ray of light is subjec reflecting surface. The path of the rays can be constructed if we know the two simple laws which govern the changes in direction: the law of refrac- tion which was discovered by Snellius a few hundred years ago, and the law of reflection with which Archimedes was familiar more than 2,000 years ago

Anthropology and Moral Relativism Two stories: In 1960's and 70's a prominent Harvard psychologist named Jerome Bruner decided that it would be a good idea to expose young people to some of the concepts of social science, so he developed a curriculum called \Man: A Course

Symbolism and Ritual It's a huge topic, it could cover a whole course 1. Two examples: a. Mariage ritual from the Kuna called\the dragging' i. Bride and groom would not choose each other, but their parents would arrange the marriage secretly. The groom's friends would traditionally surprise him and drag him down the street. (Now a days, they don't fight back so hard and they know ahead of time)

Race and Anthropology Huge topic-only going to cover a small portion of the discussion Two notions about race: Race has a biological meaning, but not a social meaning *Race has a social meaning but not biological meaning