【单选题】What does the telegram say?
A.
Return immediately for his parents missed him badly.
B.
Return immediately for his aunt is expecting him.
C.
Return immediately for something unusual happened at home.
D.
Return immediately for his uncle was seriously ill at home.
【简答题】1839 年 哪个国家 ( ) 的 Goodyear , 发明了天然橡胶的硫化
【单选题】谁发明了硫化,使橡胶工业获得突破性进展?
【单选题】Based on the scenarios below, what is the expected return for a portfolio with the following return profile?______.
【多选题】变频空调; 在常规空调的结构上增加了一个变频器。变频器是用来控制和调整压缩机转速的控制系统,使之始终处于最佳的转速状态,从而提高能效比(比常规空调节能 20%-30% ).它的特点是: 1.制冷制热的速度比常规空调快
【简答题】点的速度按规律v=v 0 +at变化.这个点在时间区间[0,T]经过多少路程?