A：该气体中可能含有C2H2
B：该气体中一定含有C2H4
C：该气体中一定没有CH4
D：该气体不可能同时含有CH4、C2H2、C2H4
Our Summer Camp
When
On July 5th
Where
A ____mountain village
Who
Stay with the____
What
In the morning, we'll learn to ____animals from the local people.
In the afternoon, we'll____about the river.
In the evening, we'll enjoy the bright____.
洋葱根尖细胞进行分裂，一个细胞分裂形成（ ）
(-2a)2 等于（ ）
