问题
选择题
— Where will you start your work after graduation?
— It's not been decided yet. I _____ continue my studies for a higher degree. [ ]
A. need
B. might
C. would
D. must
答案
答案：B
搜题请搜索小程序“爱下问搜题”
— Where will you start your work after graduation?
— It's not been decided yet. I _____ continue my studies for a higher degree. [ ]
A. need
B. might
C. would
D. must
答案：B
单质硼有无定形和晶体两种，参考下列数据：
| 晶体 | 金刚石 | 晶体硅 | 晶体硼 |
| 熔点(K) | ＞3823 | 1683 | 2573 |
| 沸点(K) | 5100 | 2628 | 2823 |
| 硬度(Moh) | 10 | 7.0 | 9.5 |
(1)晶体硼的晶体类型属于______晶体，理由是______。
(2)已知晶体硼的基本结构单元是由硼原子组成的正二十面体(如右图所示)，各正二十面体之间以B—B键相互连结，在每个正二十面体中有二十个等边三角形的面和一定数目的顶角，每个顶点各有一个硼原子。通过观察图形及推算，得出此基本结构单元是由______个硼原子构成，其中B—B键之间的键角是______。
