下列变量定义错误的是()

B.struct{intnum;intage;}teach1,teach2;

C.struct{intnum;intage;}teacher;structteacherteach1;

D.structteacher{intnum;intage;};structteacherteach1;;

A、val a = 3

B、val a:String = 3

C、var b:Int = 3 ; b = 6

D、var b = "Hello World!" ; b = "123"

A、double Stu-score=98;

B、int f(x)=1;

C、short int 2_num=79;

D、double Ave=0.0;

A、Dim 123a As Integer

B、Dom b As Double

C、Dim c1 As Singlen

D、Dim a_1,b_2 As String

A、float,double,int,long

B、double, float,int,byte

C、byte,long,double,float

D、double,int,float,long

A、（7+8）&&（9-5）

B、（9*5）||（9*7）

C、9>6&&8<10<br> D、(9%4)&&(8*3)