下列可出现慢性腹痛的疾病是()A.异位妊娠破裂 B.急性胆囊炎 C.肠穿孔 D.结核

如图所示，水平面上从B点往左都是光滑的，从B点往右都是粗糙的．质量为M和m的两个小物块（可视为质点），在光滑水平面上相距L以相同的速度向右运动，它们在进入粗糙区域后最后静止．若它们与粗糙水平面间的动摩擦因数相同，设静止后两物块间的距离为s，M运动的时间为t₁、m运动的时间为t₂，则以下说法正确的是（　　）

A．若M=m，则s=L

B．无论M、m取何值，总是s=0

C．若M=m，则t₁=t₂

D．无论M、m取何值，总是t₁＜t₂

For the safety-conscious Swedish market, a United States manufacturer of desktop computers developed a special display screen that produces a much weaker electromagnetic field surrounding the user than do ordinary screens. Despite an advantage in this respect over its competitors, the manufacturer is introducing the screen into the United States market without advertising it as a safety improvement.
Which of the following, if true, provides a rationale for the manufacturer’s approach to advertising the screen in the United States ？（）

A．Many more desktop computers are sold each year in the United States market than are sold in the Swedish market.

B．The manufacturer does not want its competitors to become aware of the means by which the company has achieved this advance in technology.

C．Most business and scientific purchasers of desktop computers expect to replace such equipment eventually as better technology becomes available on the market.

D．An emphasis on the comparative safety of the new screen would call into question the safety of the many screens the manufacturer has already sold in the United States.

E．Concern has been expressed in the United States over the health effects of the large electromagnetic fields surrounding electric power lines.

用于档案杀虫的熏蒸剂有()

A．666

B．DDV

C．除虫菊粉

D．环氧乙烷

在一般网络管理模型中，一个管理者可以和多个______进行信息交换，实现对网络的管理。

患者，女性，40岁，心悸，气促2年，查体发现心尖部舒张期隆隆样杂音，胸骨左侧第2肋间舒张早期哈气样杂音，S1增强，P2亢进，分裂。

[假设信息]如该患者出现原因不明发热，全身大关节疼痛，查体：体温39.8℃，贫血貌，双肺阴性，心脏在原心尖部舒张期杂音基础上可闻及3/6级收缩期吹风样杂音，肝脾肋下均可及，余无阳性体征，血常规检查：血红蛋白88g/L，白细胞18×10⁹/L，尿蛋白(+)，沉渣镜检RBC2～4/HP，该患者目前诊断首先应考虑

A．风湿热

B．感染性心内膜炎

C．肺炎

D．泌尿系感染

E．肝炎