题目

Directions: For eachblank in the following passage there are four words or phrases marked A, B, Cand D. Fill in each blank with the word or phrase that best fits the context. Molecular biologist Elizabeth Blackburnshared a Nobel Prize for her research on telomeres (端粒)—structures at the tips of chromosomes(染色体)that play a key role in cellular aging.1 she was frustrated that the important healthimplications of her work weren't reaching beyond academia. So along with psychologist Elissa Epel, shehas published her findings in a new book 2 a general audience -- laying out a scientificc下列生活中的变化，属于化学变化的是（ ）A．石蜡熔化B．粉笔折断C．纸张燃烧D．车胎爆炸