Euthanasia has been a topic of controversy in Europe since at least 1936. On an average of six times a day, a doctor in Holland practices "active" euthanasia: (1) administering a lethal drug to a (2) ill patient who has asked to be relieved (3) suffering. Twenty times a day, life prolonging treatment is withheld or withdrawn (4) there is no hope that it can (5) an ultimate cure. "Active" euthanasia remains a crime on the Dutch statute books, punishable (6) 12 years in prison. But a series of court cases over the past 15 years has made it clear that a competent physician who (7) it out will not be prosecuted.
Euthanasia, often called "mercy killing", is a crime everywhere in Western Europe. (8) more and more doctors and nurses in Britain, Germany, Holland and elsewhere readily (9) to practicing it, most often in the "passive" form of withholding or withdrawing (10) The long simmering euthanasia issue has lately (11) into a sometimes fierce public debate, (12) both sides claiming the mantle of ultimate righteousness. Those (13) to the practice see themselves (14) sacred principles of respect for life, (15) those in favor raise the banner of humane treatment. After years (16) the defensive, the advocates now seem to be (17) ground. Recent polls in Britain show that 72 percent of British (18) favor euthanasia in some circumstances. An astonishing 76 percent of (19) to a poll taken late last year in France said they would like the law changed to (20) mercy killings. Obviously, pressure groups favoring euthanasia and "assisted suicide" have grown steadily in Europe over the years.
4（）
A.though
B.when
C.that
D.since
参考答案：B
解析：
[注释] 逻辑搭配。根据上下文的逻辑意思，此处应由when引导时间状语从句，来表明主句中行为发生的时间。