单选题
Severe winter storms have worsened the nation's usual post-holiday blood shortage, 26 an urgent call today for people to donate blood. Type O blood is the most urgently needed, because it is the 27 blood type, meaning it can be safely 28 to most people in an emergency. 'The severe winter weather has forced the cancellation of blood drives and limited our 29 to collect blood,' American Red Cross President Elizabeth Dole said. The Red Cross reported having less than one day's supply of Type O blood on hand in 18 of the organization's 38 collection regions. The Red Cross 30 about half of the nation's blood supply. America's Blood Centers, which supplies most of the rest, also has reported shortages. Reacting to the shortage, a Pittsburgh blood bank asked 40 hospitals in western Pennsylvania, West Virginia and Ohio to 31 elective surgeries through Wednesday. At least 1,000 donors are needed each day for the next several days to stabilize the supply, said Mark Lynch, spokesman for the Central Blood Bank. 'We're talking about (postponing) hip replacement, for example, and orthopedic cases. These are sick people who need surgery, but it's not life 32 ,' he said. When its blood supply is 33 , the blood bank needs about 700 donors each day to maintain normal inventory. The Pittsburgh blood bank last asked hospitals to postpone elective surgeries because of a blood shortage in October 1995. Such procedures were canceled for almost a week. Nationwide, donations typically fall off during the holidays, when donors become too busy to give blood 34 . Bad weather increases shortages both by 35 blood drives and by causing increased blood demand to treat accident victims. A. threatening B. popular C. postpone D. regularly E. receives F. ability G. universal H. refuse I. transfused J. stable K. immediately L. prompting M. blocking N. density O. provides
问答题
【正确答案】L
【答案解析】语法判断：分析句子主干可知，空格前是一个成分完整的分句，空格后是名词短语，因此空格处应填现在分词，作伴随状语。 语义判断：符合语法条件的三个选项threatening、prompting和blocking中，只有prompting与句中的blood shortage和an urgent call today for people to donate blood相对应，prompt意为“促使，催促”。故选L。