以下四组用户标识符,其中合法的一组是

A．void define +WORD

B．a3_b3 _123 YN

C．for -abc Case

D．2a DO sizeof

E．B

F．2

A.a3_b3

B.void

C._123

D.IF

A.long

B._2Test

C.3Dmax

D.data

A.voiddefine+WORD

B.a3_b3_123YN

C.for-abcCase

D.2aDOsizeof

A.do，xyz，_printf

B.3a，_tt，IF

C.void，ff，s_v

D._pi，IF，big_tree

A．#_pound

B．_underscore

C．5Interstate

D．Interstate5

E．_5_F.cla

A．Michael Jordan

B．Su-30

C．Beckham

D．class_01

E．B52

A.void,define,WORD

B.A3_B3,_123,ab

C.FOR,-abc,Case

D.2a,Do,Sizeof