【单选题】传统的动物资源保护措施主要是划定保护区或建立保种基础。这些措施能很好地保护物种的多样性,但也存在一些缺点:保护区面积大,偷猎现象屡禁不止;建立良种基地保护地方品种投资大,时间长,容易出现近亲繁殖、物种衰退等现象。试管、克隆、冷冻保存等生物技术新成果的问世,为动物遗传资源的保护和利用开辟了新途径,建造“动物诺亚方舟”不再是天方夜谭。 这段文字主要介绍了()
【单选题】Since the September 11 attack, US President George W. Bush has 【21】______ himself as a superpower leader of hard resolve, tolerating no 【22】______ to his goals-until he came up against Israel. 【23】___...
【单选题】要使某图层与其下面的图层合并并可按( )快捷键。
【单选题】How ________the woman is to save the boy from the danger of earthquake.
【单选题】It was() late to save the drowning boy as he had gone down for the third time.
【单选题】The passer-by jumped into the cold water to save the _____ boy, who cried for help, but it was too late and the boy was _______ at last.
【单选题】在下面一段话的空缺处依次填入词语,最恰当的一组是 ( ) 中国文学具有源远流长、 ▲ 的特点。若论文学的悠久,只有古希腊文学、古印度文学可以与中国文学比肩;若论文学传统的绵延不断,任何别的国家和民族的文学都不能与中国文学 ▲ 。中国文学一直以丰富的作品、持久的魅力 ▲ 着全世界。
【单选题】In job sharing the partners should______.
C.
know each other very well
D.
have similar working experience
【单选题】下列激素中,可直接促进肾远曲小管和集合管重吸收Na+的是()
【单选题】I don’t know how they ____the first couple of weeks after the strong earthquake.