根据现代生物进化理论，物种形成的基本环节不包括
A：突变和基因重组
B：自然选择
C：生存斗争
D：地理隔离和生殖隔离
福建各地族谱中大量关于入台族裔回乡请祖先牌位赴台的记载，此类现象在清乾隆年间骤然增多，这说明乾隆年间（ ）
— How many ________ were on the bus when the accident happened?
— About forty. Seven of them were kids.
