下列计算正确的是 [ ]
A.a2a3=a6
B.(a2)3=a6
C.a6﹣a2=a4
D.a5+a5=a10
答案:B
波长的计量单位是()。
A.m,cm,mm,mu,A
B.m,cm,mm,μm,A
C.m,cm,mm,u,mu
D.m,cm,mm,μm,nm
E.m,cm,mm,μm,mu
— You look sad. ____?
— Oh, my grandmother’s very ill.
A.What’s up
B.How are you
C.What’s that
D.How about you