—No, I _______ it for 2 years.
A: had
B: have had
C: bought
D: have bought
天气晴朗的早晨,摘取一植物的叶片甲,于100℃下烘干,称其质量为A克,到黄昏时,再取同一株上着生位置、形状都和甲相同的叶片乙,同样处理,称其质量为B克,则结果是( )
直接写得数。
14-7=____
26+30=____
52-10=____
54+9=____
72-(2+18)=____
91-(35-5)=____