—Which one? The one with ______ umbrella?
A:a; the
B:the; an
C:the; a
利用图7-9-11装置做“验证机械能守恒定律”的实验.
图7-9-11
横线上最小填几?
____ 45÷8>100 ____ 203÷5>1000 ____ 36÷6>50
12:15=5:2