Htaccess … Redirect To Another Wp Page Without Url Change

Need an .htaccess export to help me combine an htaccess script I have that works with non-WP files so that it will work as part of the WordPress htaccess.

I want to be able to use the URL http://domain.com/url-to-show/?1=a& b=2
and have it display the wordpress page http://domain.com/page-to-use/
without changing the URL, and with passing the URL parameters

In my non-wordpress section I can use something like:

#RewriteEngine On
#RewriteRule ^/url-to-show/$ /page-to-use/?$1 [NC,L,QSA…