Unless you apply for a very specific project that needs very specific knowledge, knowing a language well is not going to help you much. You need to be able to show that you have a good logic, that you are able to solve problems quickly and efficiently. Most of the time, this can be done in many languages, and most projects have different parts done in different ones. Knowing the syntax to one language doesn't help you much when you have to code in another one. Logic on the other hand works everywhere. Good thinking is what is needed to find good solutions to problems... and many languages can be used. Sometimes, a specific language will be better than another one, that's where good thinking and logic will be useful. You can always refer to Google for syntax examples, and good thinking and logic will help you filter out most of the crap and find the good examples.
When I'm helping HR decide on who they hire, I always ask the person we interview logic questions, ask them to find solutions to problems I've encountered in the past and see what they come up with. If they find a working solution it's good. If they propose a solution I've actually put in production and I think was the best, it's even better (compatible thoughts, good for team work). If they find a solution I consider better than mine, then it's excellent.
This, of course, doesn't tell me how good they actually are at implementing them, but I can always coach them, and if they do have good thinking and logic, they will eventually become good at it. Though frankly, those who showed good thinking in interviews were usually the fastest learners too and I rarely had a problems with people hired using this technique.