A:石墨比金刚石稳定
B:金刚石比石墨稳定
C:1mol石墨比1mol金刚石的总能量高
D:1mol石墨和1mol金刚石的总能量相等
找出所给问句的对应答语。
①Can I help you? ____ A. I'd like some oranges.
②What do you need? ____ B. Three.
③How many books do you want? ____ C. Yes, I think so.
④Is that all? ____ D. Yes, I need some milk.
⑤What would you like? ____ E. I need some fish.
下列一元二次方程中,没有实数根的是( )
在做“伏安法测量定值电阻”的实验中,小明同学设计了如图甲所示的电路,请你完成下列问题.
下列有关生物在生物圈中的作用,说法错误的是( )