Translate the following sentences into English.
不少科学家已经意识到威胁生存环境的事实，多次向全国人民发出了警告。(sound)
【正确答案】：
MANY SCIENTISTS HAVE REALIZED THE FACTS CONCERNING THE DANGERS TO THE LIVING ENVIRONMENT AND HAVE REPEATEDLY SOUNDED A WARNING TO THE WHOLE NATION.
【题目解析】：
意识到have realized； 生存环境living environment。