图所示电路完成的逻辑功能是(  )。 A: F=+BC   B: F=BC C: F=A D: F=

函数F=AB+BC，使F=1的输入ABC组合为( ) A: BC=000 B: BC=010 C: BC=110 D: BC=101

在导线ABC中，BA、BC的坐标方位角分别为205°30′和119°30′，则右夹角∠ABC为（

当前电路的逻辑表达式是（）[img=555x308]17e43c012cc9cfe.png[/img] A: F=A'B'C+A'BC'+AB'C'+ABC B: F=A'B'C'+A'BC'+AB'C'+ABC C: F=A'B'C+A'BC'+AB'C'+AB'C D: F=A'B'C+A'BC'+AB'C'+ABC'

函数F=AB BC AC

有8个顺串，每个顺串的第一个记录的关键码分别为14，22，24，15，16，11...0132bc5fcda0dbca.png

In 1803 the United States purchased Louisiana from _____.

秦汉时期已经开始发展铁器成型技术，这句翻译为（ ） A: Iron casting technology has already been employed in Qin (220 to 205 BC) and Han dynasties (206 –220 BC). B: Iron casting technology has already been employed in Qin (221 to 207 BC) and Han dynasties (236 –210 BC). C: Iron casting technology has already been employed in Qin (221 to 207 BC) and Han dynasties (202 –220 BC). D: Iron casting technology has already been employed in Qin (221 to 207 BC) and Han dynasties (201 –227 BC).

‍秦汉时期已经开始发展铁器成型技术，这句翻译为（ ）‌ A: Iron casting technology has already been employed in Qin (220 to 205 BC) and Han dynasties (206 –220 BC). B: Iron casting technology has already been employed in Qin (221 to 207 BC) and Han dynasties (236 –210 BC). C: Iron casting technology has already been employed in Qin (221 to 207 BC) and Han dynasties (202 –220 BC). D: Iron casting technology has already been employed in Qin (221 to 207 BC) and Han dynasties (201 –227 BC).

如图.在梯形ABCD中，AD//BC，∠B=90°，∠C=45°，AD=1，BC=4，F为AB中点，EF//DC交BC于点F，求EF的长.