Please correct these English sentences

He doesn't even know how to code in HTML , let alone the thought of coding in JAVA.
I can't even talk to her properly , Let alone my idea of proposing her.

Please also tell me the alternatives for "Let alone". Some Indians , use "forget it " or "leave it" instead of "Let alone"

I think "the thought of " is wrong here.. there should be more appropriate ways.

best regards,

THe use of "let alone" is not wrong in itself. The problem with your sentences is incorrect grammar. Sentences in ENglish are generally structured as <subject> <verb> <object>.. example: I eat meat. Let alone is an idiom that can be used to join 2 seperate sentences together. So, you can say

"He doesn't know how to code in HTML. He cannot even think of coding in Java"

Each of these sentences is complete on it's own. Now, you could join them with "let alone" but you need to make sure that you follow the correct sentence structure. SO, it will be

"He doesn't know how to code in HTML, let alone think of coding in Java"

I find the merits of HTML coding and Java coding to be distinctly different. Some people can paint pretty pictures (HTML) and other people are best in back-end processing (Java).

In England one would usually contract the second part of the sentence:-

Campbell does't know how to write code in HTML, let alone Java.

But that changes the meaning. Your sentence means that you don't know how to write code in HTML, and you don;t know how to write in Java. The original wanted to express that the subject can't even think of coding in Java. Your sentence dilutes the sentiment.

Jayesh A Lalwani wrote:But that changes the meaning.

Arguably, Campbell's version makes more sense than the original, though. The intent is likely to compare one's ability in the two languages, not one's ability in A with one's ability to think about B. (Thinking about coding in any given language should be easier than coding in any particular one.)

I can't even talk to her properly , Let alone my idea of proposing her.

Aside from the same verb/noun issue, "propose" needs a preposition: "...propose to her."

Maybe because I know the OP's original language, and that's why I'm reading the intent differently. Saying someone can't even think about doing something is a lot stronger that saying that the person can't do that thing. Maybe you can;t code in Java because you are tired today.. or you don;t have an IDE. But, not being able to even think of coding in Java takes it to a whole new level. It's like there's something wrong with your brain. There's a Java sized hole in your brain that prevents you from thinking of coding in Java.

If the intent of the OP was to compare the ability to code in HTML with the ability to code in Java, then the OP would have phrased it differently.

If you are going to use the 'let alone' conjunction, it implies that the latter action is much more difficult or much more specific than the former.
So your second example which I would rewrite as
I can't even talk to her properly , let alone propose to her.
is a good use of it. Proposing involves talking, so if you can't talk to her you definitely won't be able to propose to her.

Your first example is a bit more debatable. It implies that if you can't write HTML code, you shouldn't even think about trying to write Java code.
If you accept the premise that writing Java is more difficult than writing HTML, then I think what Campbell rewrote it as has the same meaning.

Normally the two things are related when you use 'let alone' as has been discussed. But it can also be used with unrelated tasks usually in the context of making an insult. Such as:

"He can barely tie his own shoelaces, let alone run a company"

thank you all for your time and wonderful explanations.