大家好，我试图知道如果给我的测试代码是正确的，或者如果我没有正确下载我的dosbox. The error says“Operand types do not match”这个代码是由我们的在线类instructor给我们测试，如果我们正确下载dosbox.他一直说，他给的代码没有什么问题，请帮助我. Here's the code.

.model small
.stack 100h

.data
    num1 dw ?
    num2 dw ?
    result dw ?
    operator db ?
    msg db 0Dh, 0Ah, "Input your first number: $"
    msg2 db 0Dh, 0Ah, "Input your second number: $"
    msg3 db 0Dh, 0Ah, "Input the operator (+, -, *, /): $"
    msg4 db 0Dh, 0Ah, "Result: $"

.code
    mov ax, @data
    mov ds, ax

    ; Input your first number
    mov ah, 09h
    lea dx, msg
    int 21h

    mov ah, 01h
    int 21h
    sub al, '0'
    mov num1, ax

    ; Input your second number
    lea dx, msg2
    int 21h

    mov ah, 01h
    int 21h
    sub al, '0'
    mov num2, ax

    ; Input your operator
    lea dx, msg3
    int 21h

    mov ah, 01h
    int 21h
    mov operator, al

    ; Perform arithmetic operation
    cmp operator, '+'
    je addition
    cmp operator, '-'
    je subtraction
    cmp operator, '*'
    je multiplication
    cmp operator, '/'
    je division

    ; Display error message for invalid operator
    mov ah, 09h
    lea dx, msg4
    int 21h

    mov ax, 4C00h
    int 21h

addition:
    mov ax, num1
    add ax, num2
    mov result, ax
    jmp display_result

subtraction:
    mov ax, num1
    sub ax, num2
    mov result, ax
    jmp display_result

multiplication:
    mov ax, num1
    mul num2
    mov result, ax
    jmp display_result

division:
    mov ax, num1
    mov bx, num2
    xor dx, dx
    div bx
    mov result, ax
    jmp display_result

display_result:
    mov ah, 02h
    mov dl, result
    add dl, '0'
    int 21h

    mov ax, 4C00h
    int 21h
    
end

字符串
我试过配置东西，但因为这是我第一次使用汇编，我还不知道从哪里开始。