【正确答案】:
IN THE COMING 21ST CENTURY MANKIND WILL HAVE NEW OPPORTUNITIES TO DEVELOP AND UTILIZE THE OCEAN.
【题目解析】:如果用定语从句的话,which前面应该加in;如果不用定语从句,可以将时间用介词结构表达。
IN THE COMING 21ST CENTURY MANKIND WILL HAVE NEW OPPORTUNITIES TO DEVELOP AND UTILIZE THE OCEAN.