Head section
First of all, you should be careful when you paste the first google Adsense code provided by google adsense. You should paste this code to between the <head></head> of your website. Don’t paste a code that was modified. The Adsense code should be taken from a google page.
Multilingual websites problem
Then, if you have a multilingual website, paste the google Adsense code to pages in the same language. Don’t paste the google Adsense code to other pages in different languages. Ideally, it is better to start with one language only. Once, we added the Google adsense code to a website in both French and English. Without giving any reasons Google rejected our Adsense application.
Check your pages
Don’t add any content that could infringe the Google Adsense terms. For example, you should ensure that there is no pictures with nudity. The Google adsense program policies often change. I do encourage you to read it again if you have read a long time ago.