单选题 It was _____ the chief engineer came _____ we began the experiment.
not until; that
not until; then
until; that
until; when
单选题 It was _____ she was sick _____ she didn’t come to attend the farewell party.
because; why
why; that
since; that
because; that
单选题 In developing countries, _____ at least 16 cities are expected to have more than 12 million people _____ by the end of this decade, failing to give priority to public transport would be disastrous.
where; each
which; /
that, everyone
in which; anyone
单选题 Libraries have reference books _____ you can check out a physician’s educational background, training, and other credentials.
from that
in which
through that
by which
单选题 Written in central Canada in the early part of the twentieth century, _____, depicts life in Manitoda.
The Midnight Sun was Victor Frank’s last novel
Victor Frank’s last novel was The Midnight Sun
The Midnight Sun, which was Victor Frank’s last novel
Which was Victor Frank’s last novel, The Midnight Sun
单选题 已知某二阶非齐次线性微分方程的三个解分别为y1=ex,y2=xex,y3=x2ex,则它的通解为( )。
y=C1(x-1)ex+C2(x2-1)ex+ex
y=C1(x-1)e-x+C2(x2-1)ex+ex
y=C1(x-1)ex+C2(x2-1)e-x+ex
y=C1(x-1)ex+C2(x2-1)ex+e-x
单选题 设函数y1(x)、y2(x)、y3(x)线性无关,且都是二阶非齐次线性方程y″+p(x)y′+q(x)y=f(x)的解,又c1与c2为任意常数,则该非齐次线性方程的通解可表示为( )。
c1y1+c2y2+y3
c1y1+c2y2-(c2+c1)y3
c1y1+c2y2-(1-c1-c2)y3
c1y1+c2y2+(1-c1-c2)y3
单选题 微分方程y″-2y′+2y=ex的通解为( )。
y=ex(c1cosx+c2sinx)+ex
y=ex(c1cosx+c2sinx)-ex
y=ex(c1cosx-c2sinx)+ex
y=ex(c1cosx-c2sinx)-ex
单选题 一定量的理想气体,分别经历如图(a)所示的abc过程,(图中虚线ac为等温线),和图(b)所示的def过程(图中虚线df为绝热线)。判断这两种过程是吸热还是放热( )。
abc过程吸热,def过程放热
abc过程放热,def过程吸热
abc过程和def过程都吸热
abc过程和def过程都放热
单选题 如图所示,一定量的理想气体,从p-V图上初态a经历(1)或(2)过程到达末态b,已知a、b两态处于同一条绝热线上(图中虚线是绝热线),则气体在( )。
(1)过程中吸热,(2)过程中放热
(1)过程中放热,(2)过程中吸热
两种过程中都吸热
两种过程中都放热
重垢洗涤剂和轻垢洗涤剂的组成有何不同?
子宫内膜异位症引起不孕症的重要原因是()
对于UAP项目的访问url,正确的格式为()
集中供热由于规模比分散供热大,因此对环境污染也更大。
针对业务(1)~(3),下列处理正确的是( )。
女性,60岁,近2个月出现阴道流血。查体:患者呈肥胖体态,体重91kg,身高161cm,BP152/95mmHg,T37.2℃,心、肺检查正常,腹部肥大,未触及肿块。妇科检查:外生殖器正常,阴道无异常,宫颈光滑,子宫似正常大小,附件未触及肿块。56岁绝经,GP,并患高血压病,现口服降压药物治疗,既往曾有PCOS病史。其母亲死于乳腺癌。该患者术前MRI检查示子宫前壁病灶直径为2cm,侵蚀深度为1/3肌层,下缘达宫颈内口下0.5cm,深达0.5cm。最佳处理方案是( )
牵制战术的定义是:一方的远射程子力在直线、横线或斜线上攻击对方掩护王或其它棋子及要害格子的棋子,使它不能行动或难以行动的战术。根据该定义,可以实施牵制战术的棋子有()。
LPF型防爆光电脉冲发讯器供电电源是()。
对讲机检查的要点是什么?
简述我国的经济文化类型划分。