∵(a-3)2=3-a，
∴a-3≤0，
解得a≤3，
故答案是a≤3．
一个数除以25%后，再乘25%，结果大小不变。[ ]
The science Festival is an occasion _____ model planes and model rockets are flown over the school grounds.
A．that
B．when
C．where
D．which
