A:硫酸铵
B:尿素
C:草木灰
D:硝酸钾
2.3+5.6=____ 16+23= ____ 98÷4= ____
7.8+0.9-1.4= ____ 1.2×1.3÷2= ____
28-13×2= ____ 34-512×67= ____
— It's dangerous to swim here. Look at the sign.
— Oh, I notice it. Thanks for telling me.