How the word "useful" is translated into English
A thermos is very useful on long trips.
[ə ˈθɜrməs ˈɪz ˈvɛri ˈjusfəl ˈɔn ˈlɔŋ ˈtrɪps.]
Here's a useful tip for making tea.
[ˈhɪrz ə ˈjusfəl ˈtɪp fər ˈmeɪkɪŋ ˈti.]
That cup isn't very useful because it's too small.
[ˈðæt ˈkəp ˈɪzn̩t ˈvɛri ˈjusfəl bɪˈkɔz ˈɪts ˈtu ˈsmɔl.]
"useful" is in the lesson "Drinks" (Level 40), along with 11 other useful words. LinDuo has 180 topic lessons like this one, 2,375 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.