对于碳素钢,当含碳量小于()%时,称为低碳钢或普碳碳素钢。
A.0.77
B.0.60
C.0.25
参考答案:C
下列各项比较中,错误的是
A.原子半径:Li < Na < K
B.酸性: H2SiO3 < H2CO3 < HNO3 < HClO4
C.稳定性: SiH4 > H2S > HF
D.碱性: NaOH > Mg(OH)2 > Be (OH)2
It will be bad for your health to eat_______food and take_______exercise.[ ]
A. fewer; more
B. more; less
C. little; much
D. less; more