我国三大自然区的划分依据主要是( )
A:气候、水文两大要素
B:生物、土壤两大要素
C:地貌、气候两大要素
D:地貌、生物两大要素
—What's that?
— an elephant.
假定五对等位基因自由组合,则杂交组合AaBBCcDDEe×AaBbCCddEe产生的子代中,有一对等位基因杂合、四对等位基因纯合的个体所占的比例是
i是虚数单位,复数1-3i1-i为( )
根据首字母提示完成下列短文。
A good class monitor gets on well w____ classmates and likes to h____ others. He often cleans the classroom and makes the classroom c____ just like h____. C____ him to be your monitor.