问题
选择题
| With tags (标签) _____ to the luggage, it won't take long for the passengers to find theirs correctly. |
A. attaching B. attached C. to attach D. attaches |
答案
答案：B
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| With tags (标签) _____ to the luggage, it won't take long for the passengers to find theirs correctly. |
A. attaching B. attached C. to attach D. attaches |
答案：B
根据已有内容的规律进行增补
（1）同族元素单质间的置换反应的化学方程式：
①2Na+2H2O=2NaOH+H2↑ ②2HBr+Cl2=2HCl+Br2 ③2H2S+O2=2S+2H2O ④______
（2）已知
| 化学键 | Si-O | Si-Cl | H-Cl | Si-Si |
| 键能/KJ•mol-1 | 460 | 360 | 431 | 176 |
①比较熔点SiCl4______SiO2（填“＞”或“＜”），
②工业制纯硅反应：
SiCl4（g）+H2（g）=1 2
Si（s）+2HCl（g）△H=+118KJ•mol-1则H-H键能为______KJ•mol-1．1 2