一、选择题(在下列各题中,选择出符合题意的答 案,将其代号填入括号内)(每小题2分30分) 1已知反应Cu+4HN03(浓)Cu(N03+2N2(g)+2H20,若 有4.00 mol HNO33被还原,则产生的NO2气体在273℃、202ka下所占 ( 24()449(89.9:()180L

一、物质循环的一般特点 二、水循环 三、气体型循环 四、沉积型循环 五、有毒有害物质循环

一、改善样品的挥发性和热稳定性 二、改善样品的峰形 三、提高分离性能 四、增加分离检测的选择性和灵敏度

5.1概述 5.2大气污染源及污染类型 5.3大气污染的危害 5.4大气污染的防治

本病是一慢性呼吸传染病。主要症状为咳 嗽和气喘,病变特征是肺的尖叶、心叶、中间 回本章叶、膈叶前缘呈“肉样”式虾肉样变。 很多国家报道了本病。长期以来该病被认为 回本节是最常发生和经济意义重大的猪病之一饲料 利用率降低20-25%,增重减少2.5-16%

一、植物与环境 1、有关环境的概 （1)环境: （2)生态因子:光照、温度、水分、土壤、大气因子。 （3)生境: （4)生存条件:

1 For the circuit given in Fig. 18-14, the R C2, fc are given find the switched capacitor equivalent

characteristic is assumed to be as shown in Fig. 17-15b 1 Sketch the characteristic of each of the following circuits shown in Fig. 17-31. the diode characteristic is shown in Fig. 17-3le 2 Sketch the transfer characteristic of each of the following circuits shown in Fig. 17-32 the transfer characteristic being vo/v

1 Find the matrix equation in the circuit of Fig. 16-12 by nodal analysis method. Assume that each branch admittance of the circuit is 1S

1 Find F(s) if f(t) = (a)(t-3);(b)4t u(t-3); (c)4 cos to(t-3). 2 Obtain partial-fraction expansions for each of the following rational functions, and find the corresponding time functions: