I used several phrasal verbs (e.g. pick up, look out for, turn off, carry on) in my description in yesterday's lesson.
These verbs look easy, but they are good examples of the kind of natural, idiomatic language that native speakers use. The tricky thing about phrasal verbs is that you have to learn what each one means; you can't understand them by translating the individual words.
For example, I used "pick up" to mean "collect" (I was waiting for my colleague to collect me), but "pick up" can also mean improve, learn quickly, or receive. Have a look at this page on a grammar website. Can you see why phrasal verbs might impress the examiner if you use them correctly?