问题
选择题
There are many _____ for visitors to the beach. [ ]
A. ride boat
B. boat ride
C. boat rides
D. the boat rides
答案
答案：C
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There are many _____ for visitors to the beach. [ ]
A. ride boat
B. boat ride
C. boat rides
D. the boat rides
答案：C
在①乙烷；②乙烯；③乙炔；④苯的分子中,有关碳碳键叙述正确的是
| A．键长:①>④>②>③ | B．键能:①>②>③>④ |
| C．一个C=C双键的键能等于两个C-C单键的键能之和 | |
| D．一个C≡C叁键的键能大于一个C=C双键和一个C-C单键的键能之和 |