Be careful not to damage other people's property.
小心别损及别人的财物。
It would be unfair not to let you have a choice.
不让你有所选择是不公平的。
Be careful not to cross the line.
小心别越过道路的中界线。
Be careful not to confuse quantity with quality.
注意不要把数量与质量混淆了。
Be careful not to drop that plate.
小心别把盘子摔了。