укажите в каждой строке те слова которые читаются по одному и

6) summer cut plum butter

In each of the word there is the vowel u. In all four words this vowel is in the close syllabus. It means that it is pronounced as the sound [] with no exceptions.

Odd words in each of the rest lines:

1) hell she pet hen she [i].

2) huge lunch duke costume lunch [].  

3) hurly-burly nurse puppet Thursday puppet [].  

4) meal cheese free set set [e].

5) computer cut plum butter computer [ju].