问题详情

(教材课文原文)
{A. By; B. In; C. Until} 2050, the world"s population {A. projected; B. is projected; C. has been projected} to rise to 9 billion from just over 7 billion currently. Proponents of genetically modified foods say they are safe and can boost harvests {A. even though; B. even; C. though} in bad conditions by protecting against pests, weeds and drought. This, they argue, will be essential to meeting the needs of a booming population in decades to come and avoiding starvation.
{A. Furthermore; B. Moreover; C. However} Doug Gurian-Sherman, senior scientist for the food and environment program at the Union of Concerned Scientists, an advocacy group, said genetic engineering for insect resistance has provided only a modest increase in yields since the 1990s and drought-resistant strains have only {A. modestly; B. modest; C. moderate} reduced losses from drought.