Thanks for your proposals. Regarding #16 and #15 I am not convinced by th 4 with the star. It sounds like too much US oriented, while our company teaches US and UK english. Please take out the star from #16 Regarding #13 I think it is too chaotic, too many symbols.
Thanks for you new proposals. regarding #19 #20 #21 #22 I think the big 4 is confusing. #23 the symbol you used reminds me something related to tlc / cell phones. #33 and #32 are good.