【单选题】下表是一些共价键的键能(kJ/mol)数据, 以下表达中肯定正确的是 共价键 键能 共价键 键能 H-H 436 H-F 565 C-F 427 H-S 339 C-Cl 330 H-Se 314
C.
相同条件下CH 3 F比CH 3 Cl更易发生水解反应
D.
相同压强下,H 2 S的沸点比 H 2 Se的沸点高
【简答题】Express these system specifications using the propositions p “The message is scanned for viruses” and q “The message was sent from an unknown system” together with logical connectives (including negat...
【单选题】图7是2015年寒假期间某位驴友在云南拍摄到的“孤峰残丘油菜花”。图8为“岩石圈物质循环”示意图,甲乙丙丁戊分别表示各类岩石和岩浆,abcde分别表示各种地质作用。据此完成7-8题。 7、关于图7地区自然地理特征及其原因的分析,叙述正确的是 ( )
【单选题】处在同一发展阶段的不同地区,甚至同一地区的不同城市,城市的分布和发展的状况也有差异,()在这种差异的塑造中起了很大的作用。
【单选题】Which of the following statements about research and development expenditure are correct? 1 Research expenditure, other than capital expenditure on research facilities, should be recognised as an expe...
【单选题】Whose voice does Crusoe hears calling his name when he returns to shore in his second canoe?