这个外国地名的发音太难了，我试了好几次都说不准。

The name of that foreign place is so ___unpronounceable that I've tried several times and still can't say it right.

这个化学物质的学名太长又复杂，几乎无法正确发音。

The scientific name of this chemical is so long and complex that it's almost ___unpronounceable.