以下是对杨阳同学部分生活事例的分析，其中合理的是（ ）
A：去游泳馆游泳时，受到水的浮力约为2000N
B：全家6月份自来水用量26m3，算出其质量为26kg
C：从一楼走到三楼家中，克服自身重力做功约为100J
D：参加800m跑步的成绩是4min10s，则她跑步的平均速度是3.2m/s
Are these his shoes? No, they____ (aren't/are).
His pronunciation is better, for he kept ______ a short passage after the tape every morning.
