A:①②
B:③④
C:①③
D:②④
0.5÷0.9____0.5
0.55×0.9____0.55
36÷0.01____3.6×100
7.3÷0.3____73÷0.3.
伽利略斜面实验中:
— Why don't you ________ a hobby like painting or taking photos?
—Didn’t you see the ______, sir? Smoking is not allowed here!