题干
The English teacher isn't here. She ________ to the office.
A：has been
B：has gone
C：went
D：did go
答案(点此获取答案解析）
B
The English teacher isn't here. She ________ to the office.
A：has been
B：has gone
C：went
D：did go
B（g）+ 2C（g），且达到平衡。当升高温度时，气体的密度增大，则下列叙述中正确的是（ ）