【单选题】In many countries, ownership of a registered trademark can only be acknowledged after the mark has gone uncontested for a certain long period of time.
【单选题】据《2019年世界毒品问题报告》,有2.71亿人在前一年使用过毒品,其中大多数是( )。
【单选题】In many countries in the world
A.
medical school degree is not enough for a medical license.
B.
further exams are necessary only when physicians want to become experts.
C.
a licensed physician can practice medicine only within his province.
D.
only staff members can admit patients to the hospital.
【判断题】维生素B 2 极易溶于水,酸性溶液中对热稳定,在碱性溶液中易于被分解破坏,游离型对紫外光高度敏感。
【单选题】In many countries in the world ,breakfast is a snack____a meal,but the traditional English breakfast is a full meal [ ]
【判断题】维生素B2极易溶于水,酸性溶液中对热稳定,在碱性溶液中易于被分解破坏,游离型对紫外光高度敏感。
【简答题】阅读材料,回答下列问题。 材料一:坐落在广西壮族自治区乐业的大石围天坑群是世界上最大的天坑群。为了揭开其神秘面纱,中外科考队于2010年10月15日开始对它进行科考活动。 材料二:重庆地形图和2005年酸雨的时空分布和变化统计数据。 (1)天坑是一种分布在喀斯特地区的特殊地质景观。调查发现地下河为天坑'之母',天坑主要是地下水对_____(岩石名称)的溶蚀作用造成的。 (2)图2为乐业地区的各月平...