下列计算正确的是( )
A:a3+a2=a5
B:a3﹣a2=a
C:(a3)2=a5
D:a3•a2=a5
下列操作中,能鉴别空气、氧气和氢气3瓶气体的是
47+21=____
25+34=____
26+62=____
⑴My favourite song is the ABC song.____
⑵Tom goes to the zoo on Saturdays.____
⑶Look at the dog. It's thin.____
⑷The sweater is on the bed.____
⑸—What are they? ____
—They're trees.
A. B. C. D. E.