L1 and L2 are concurrent find k ：how to translate this sentence into Chinese?it was from a math question，k is the slope of one straight line

GMAT一道数学题（data sufficiency）If l1,l2 and l3 are lines in a plane,is l1 perpendicular to l3?(1)l1 is perpendicular to l2 (2)l2 is perpendicular to l3是不是错了? L1 and L2 are concurrent find k ：how to translate this sentence into Chinese?it was from a math question，k is the slope of one straight line 开关的L1,L2, l1,l2都垂直于同一平面,l1平行l2? 彩虹锹甲L1 L2 开关l1 l2 l3 n 灯泡L1和L2串联,灯泡L2并联一个电压表,发现灯泡L1和L2都不亮,电压表有示数,是什么原因?A:L1断路,L2短路B：L1断路,L2断路C：L1短路,L2断路D：L1短路,L2短路 英语翻译You dream a dreamBut you never wake upYou're so afraidThat the dream is overOpen your eyes and you'll seeDaydreaming won't concur meWon't concur me,no it won't concur meCause only the good guys can get,what they're coming forAnd all of th 直线L1与L2没有公共点,则L1与L2的位置关系是（ )L1与L2有且只有一个公共点,则L1与L2（ )L1与L2有两个公共点,则L1与L2（ ） L1平行L2,L1有两点AB,L2有两点CD,AC=CD=4,L1到L2距离 L1、L2并联 电流表测L1,S控制整个电路 电源开关l1.l2.l3代表啥意思 开关l1,l2.l3什么意思 开关的L1和L2是什么意思 为什么F1+L1 =F2+L2 L1,L2,L3代表什么线 开关上L1+L2+L是什么意思啊? 在图表F1 F2 L1 L2