单选题 · 选择一个答案
Besides signalling for at least 3 seconds, what must you do before changing to the lane on your left?
向左变道前，除至少提前3秒打灯，还必须怎么做？
Check mirrors and your left blind spot, find a safe gap and give way to traffic in the lane you are entering.
查看后视镜、转头检查左侧盲点，并确认有安全间距，给目标车道车辆让行。
阅读相关知识
The lane need not be empty, but you must not obstruct its users. Adjust speed smoothly; hazard or brake lights do not replace signalling and observation.
目标车道可以有其他车辆，关键是不能妨碍它们且有安全空隙。双闪或刹车灯不能替代转向灯与观察；根据交通情况平稳调整车速。