脉冲变压器不能用于()。 A.负载电阻与馈线特性阻抗的匹配 B.改变脉冲的极性

题型:单项选择题

问题:

脉冲变压器不能用于()。

A.负载电阻与馈线特性阻抗的匹配

B.改变脉冲的极性

C.隔离电源部分的直流成分

D.电源电压变换

考点:一级结构工程师基础知识电工电子技术电工电子技术题库
题型:单项选择题

The day of terror at the Virginia Polytechnic and State University in Blacksburg began at about 7:15 a. m. , with the shooting of a woman and a male resident adviser on the fourth floor of a dorm building on campus, Kristen Bensley, a freshman who lived below the floor where the shooting occurred, told TIME, "There were minors going on about the assailant was fighting with his girlfriend or something of that nature." Bensley notes that only residents can get into the building, using a specific "passport", that is, a card that one has to swipe in order to open doors before 10 a.m. If he was an outsider, someone would have had to let him in. Or more likely, he was a resident of the dorm himself. If so, how did be keep so much ammunition unnoticed

Unlike high schools, most universities can’t beef up security with a metal detector or two. So what can be done to protect students Other questions remain unanswered. Why was there a two-hour gap between the incident at the dorm and a far more fatal one across campus At one point, that led to theorizing that more than one gunman was involved. The gunman who killed at least 30 people at Norris Hall shortly after 9 a.m. was described by some sources as an Asian man.

It has been a surreal time for the students. Brandon Stiltner, a senior aerospace engineering student, and Jonathan Hess, a senior mechanical engineer, were watching TV all day but by noon they’d had enough. "We decided we needed to do something," Stiltner said. "We were worthless sitting around." So they took their six-foot Virginia Tech sign off the wall and logged into Facebook. Within the next few hours 100 people replied to their e-mail request for a vigil.

By 8 p.m. hundreds bf students began filing down the steps of the War Memorial Chapel toward the drill field. Clusters of two and three students stood together in silence. Slowly they began to line up to sign the board. "I’m still really in disbelief," says Stiltner. The shock of the day’s shootings sank in, Hess said, as he carried the sign across campus for the vigil. "It hit me," Hess said, "to know that it was in these buildings." The media crews that swarmed campus were also surreal to Hess and Stiltner. "We could look out our window and see exactly what’s on TV," Stiltner says. He watched his sign crowded with initials and prayers, awaiting the names of the victims, He shuddered. "I hope I don’t have any nasty surprises.

Which word can take place of "surreal" (Line 1, Para. 3; Line 5, Para. 4) in the passage()

A. Unbelievable

B.Unforgettable

C.Authentic

D. Miserable

题型:单项选择题

供给婴儿能量的主要营养素之间的比例按蛋白质、脂肪、碳水化合物分别为()

A.10%、20%、70%

B.20%、20%、60%

C.15%、35%、50%

D.30%、20%、50%

E.20%、10%、70%

题型:单项选择题

四妙丸是在二妙散的基础上加()。

A.牛膝、白术

B.牛膝、薏苡仁

C.牛膝、茯苓

D.牛膝、车前子

E.牛膝、桂枝

题型:单项选择题

5岁男孩,低热,干咳,皮肤结节性红斑,疱疹性结膜炎,多发性一过性关节炎及颈淋巴结肿大常见于()

A.风湿热

B.传染性单核细胞增多症

C.类风湿性关节炎

D.原发性肺结核

E.川畸病

题型:单项选择题

“曾经沧海难为水,除却巫山不是云。”出自______。

A.《离思》

B.《寒菊》

C.《示子聿》

D.《蝶恋花》

更多题库