【判断题】价格机制包括价格形成机制和价格调节机制。()
【判断题】烯烃的顺反异构体和烷烃的构象异构体一样,是相同化合物的不同空间立体形式
【单选题】I first became aware of the unemployment problem in 1928. At that time I had just come back from Burma, where unemployment was only a word, and I had gone to Burma when I was still a boy and the post-...
A.
They imagined they were to blame for being out of work.
B.
They had to live no the unemployment benefits.
C.
They should have been working instead of doing nothing.
D.
They had to admit that unemployment would probably continue
【多选题】立体异变分子具有重排现象,会产生异构分子。下列关于异构分子的形成,说法正确的是( )。
A.
金属茂中的茂环发生σ→η异变并没有明显的能量变化。
B.
羰基金属簇化合物中羰基有多种不等价的立体异变形式。
D.
“马鞍”型环辛四烯化合物在某种能量状态下会经历一个平面型的过渡态,导致“马鞍”型结构的翻转。
【单选题】( 13 ) 若唯一确定一棵二叉树,只需要知道该二叉树的 ( ) 。