（）是指社会成员从一种社会地位或职业向另一种社会地位或职业的转移。
参考答案：社会流动
句型转换。
1.He needs to lose a bit of weight.（改为否定句）
He ________ ________ to lose a bit of weight.
2.Yao Ming is a great player. Do you think so？（改为含有宾语从句的复句）
Do you think ________ Yao Ming ________ a great player.
3.I wonder what we should do next.（改为同义句）
I wonder ________ ________ ________ next.
人在摄取混合食物时，其呼吸商通常为
A．0.6B．0.7C．0.8D．0.85
needs to lose a bit of weight.（改为否定句）