It is rather ______ that we still do not know how many species there are in the world today.

I'd like to be a professional singer, but I don't think I've got

 Scientific research shows that animals can show         emotions like human beings. They are sometimes lively, and sometimes bad-tempered.

Hi, Mark. How was the musical evening?— Excellent! Ales and Andy performed _________ and they won the firs prize.

Don’t believe in those ads that you can master a language in one month. Instead, it is a(n) _______process, which may last for years.