现代生物进化理论认为生物进化的基本单位是[ ]
A.细胞
B.个体
C.种群
D.群落
答案:C
下列反应中,氧化剂与还原剂物质的量之比为1:2的是[ ]
A. 3S+6NaOH=2Na2S+Na2SO3+3H2O
B. 2CH3COOH+Ca(ClO)2=2HClO+Ca(CH3COO)2
C. I2+2NaClO3=2NaIO3+Cl2
D. 4HCl(浓) +MnO2MnCl2+Cl2↑+2H2O
We cannot ______ our offer open for more than three days, so would you please telex your acceptance.
A.have
B.place
C.remain
D.leave