Compiler errors 我这么困惑到底做错了什么？

我正在用BASIC做一个程序，我知道它真的很糟糕，我可以修复很多东西，但我想知道的是为什么我在结束SUB时会出错

' simple calculator
declare sub main
declare sub add
declare sub subtract 
declare sub multiply 
declare sub divide
declare sub question 
declare sub sendBack     'asks to send user back to main menu

main 

sub main     'Where the user makes there selection
dim choice as integer
input "Welcome, would you like to 1.Add 2.Subtract 3.Multiply 4.Divide" ; choice
if choice = 1 then 
    add
elseif choice = 2 then 
    subtract 
elseif choice = 3 then
    multiply
elseif choice = 4 then 
    divide 
else 
    print "Error 404 your choice does not exist, please enter a corresponding number!"
    main
end sub

sub question    'Get 2 integers from user 
dim num1 as integer 
dim num2 as integer 

input "Please enter your first number" ; num1 
input "Please enter your second number" ; num 2 
end sub

sub add     
question 
print num1 + num2 
end sub

sub subtract 
question 
print num1 - num2
end sub

sub multiply 

question 

print num1 * num2

end sub 

sub divide
question 
print num1 / num2
end sub

sub sendBack
dim answer 
input "Would you like to make another calculation, 1.Yes, 2.No" ; answer
if input = 1 then 
    main 
elseif input = 2 
    sleep 
else 
    print "Please enter a valid choice, thankyou!"
    sleep
end sub

我犯的错误

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你没有结束你的if陈述

IF-
ELSEIF
ELSE
END IF

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在关闭SUB之前关闭IF语句。

读取代码有点困难；您可能希望在将来粘贴之前将其正确缩进。：）

无论如何，您的问题在于语法。在每个ELSE语句及其相应的代码之后，如果需要，则需要结束

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请参阅以更好地理解此内容。

哦，很抱歉给您带来不便，我以前只使用过一次此网站，这是一个新网站，非常感谢您，没有问题。我只是想下次再把它扔出去。：）

IF-
ELSEIF
ELSE
END IF