A:x≤2
B:x<2
C:x≥2
D:x>2
按照要求作图:
(1)根据图1中通电螺线管,在磁感线上标出方向,并标出电源的右侧小磁针的N、S极.
(2)如图2所示,杠杆在力F1、F2作用下处于平衡状态,L1为F1的力臂.请在图中作出F2的力臂L2及力F1.
(3)如图3所示,a、b分别为一束入射光线和一束出射光线.请画出a经过凹透镜后的折射光线和与b对应的入射光线.
甲点(30°N,75°E)位于乙点(0°,20°W)的什么方向:
Our teachers have been with us for nearly three years _______ we came to junior high school. We should thank them for what they have done for us.