Is there a relationship between the electric field [img=14x24]1803a376c9db0a5.png[/img] and magnetic field [img=14x24]1803a376d21ab6b.png[/img] of an electromagnetic wave at each point in vacuum? A: No any relationship. B: Yes, [img=14x24]1803a376db08c62.png[/img] is perpendicular to [img=14x24]1803a376e3d9bc3.png[/img] and [img=59x19]1803a376eca6699.png[/img]. C: Yes, [img=14x24]1803a376db08c62.png[/img] is parallel to [img=14x24]1803a376e3d9bc3.png[/img] and [img=59x19]1803a376eca6699.png[/img]. D: No relationship in direction but [img=59x19]1803a376eca6699.png[/img] in magnitude.

In 1803 the United States purchased Louisiana from _____.

In 1803, President Jefferson negotiated the purchase of Louisiana from Mexico.

下面正确的字符常量是（ ） A: "a" B: '\\' C: "\n" D: "\376"

国际网球联合会成立于 A: 1903 B: 1803 C: 1913 D: 1923

霍尔效应哪一年发现的？ A: 1881 B: 1879 C: 1803 D: 1831

GPⅣ的受体（） A: APAF B: BTSP C: CFn D: DPDGF E: ECa²⁺

在茎叶图中，数值368，（）和（）是“茎”和“叶”。376

《突发公共卫生事件应急条例》(国务院376号令)什么时间公布实施的?

下面正确的字符常量是() A: "a" B: '\n' C: "n" D: "\376"