A:﹣1
B:﹣i
C:1
D:i
①有5.6g金属被腐蚀
②有6.5g金属被腐蚀
③在标准状况下有2.24L气体吸收
④在标准状况下有1.12L气体吸收.
____ ____ is it?
The students carried their books away from the school ____ ____ .