He's got himself into a dangerous situat
题型：选择题
问题：
He's got himself into a dangerous situation ___he is likely to lose control over the plane.[ ]
A. where
B. which
C. while
D. why
题型：选择题
根据下列要求作图：
（1）请在如图中画出经过透镜折射后的光线
（2）如图所示，用螺丝刀撬图钉，O为支点，请画出动力F1的力臂（L1）和阻力（F2）的示意图．
（3）如图所示，请将下列元件连接成符合安全用电要求的家庭电路．
