题干
The park gates ______ at 10:00 every evening.
A：lock
B：locked
C：are locked
D：were locked
答案(点此获取答案解析）
C
The park gates ______ at 10:00 every evening.
A：lock
B：locked
C：are locked
D：were locked
2NH3（g），平衡时测得N2的转化率为12%，则在相同温度和压强下，平衡时混合气体的体积是反应前的