【判断题】卤素对烯烃的加成反应中,碳正离子机理得到的产物,既有同向加成产物,又有对向加成产物。
【判断题】引发“五四”爱国运动的直接导火索是巴黎和会上中国的外交失败。
【单选题】What is one advantage of solar drip irrigation systems mentioned in the passage?
A.
They are more reliable.
B.
They have initial advantage.
C.
They don't break down from time to time.
D.
They are more economical over time.
【判断题】五四运动的直接导火索,是巴黎和会上中国外交的失败。
【单选题】下列关于肾蒂,错误的是
B.
其内的结构自前向后分别是肾静脉、肾动脉和肾盂
D.
其内的结构有肾动脉、肾静脉、肾盂、肾的神经及淋巴管
【单选题】Choose the word or phrase that is closest in meaning to the underlined part. NASA worked in the 1970s and early 1980s to research the possibilities of using Solar Power Satellite (SPS) systems with la...
A.
shed solar energy to the Earth’s surface from the satellite
B.
set the satellite down to the Earth’s surface with power
C.
shut down the power on the Earth’s surface from the satellite
D.
switch off power to the Earth’s surface from the satellite
【单选题】膜表面的流速增大,则浓度极化( ),截留率( )。