TEST 273The Official Cambridge Guide to IELTS · Questions 27–30Biofuel PresentationAnswer the questions below.Write NO MORE THAN TWO WORDS for each answer.What TWO biofuel-related problems do Mike and Karina decide to focus on in the last section of their presentation?–27–28Which two sources of biofuel do Mike and Karina say are being tried out?–29–algae–30