[单选题]
98.29: A 50-kg student stands on a s;pzz 7jt-m4obo5 j o/gcale in/ trlw xegl;b)e +m8w9 an elevator. At the instant the elevator has a dow;gwe xr/el8) bt ml9w+nward acceleration of $1.0\; m/s^{2}$ and an upward velocity of 3.0 m/s, the scale reads approximately
