杂交育种的基本原理是
A:基因突变
B:染色体变异
C:基因重组
D:基因分离定律
若y2=2px的焦点与x26+y22=1的左焦点重合,则p= ( )
贯穿《窃读记》全文的线索是____。
—It's not difficult for five workers to push the broken van away.
— Yes, __________.