Don't be lazy for you pronunciation

Month
When you really put your tongue between your teeth, then you can pronounce "th" right.
Normally as a Chinese, you cann't hear the difference by yourself, but English people can hear whether you do it or not, so it sound totally different.

If you let them check your pronunciation, they will keep on say, no. no no, jsut by hearing, untill you finally put your tongue between teeth.

For English pronunciation, you really need make sure all your parts in your mouth in the right position then pronounce it.