Tat may roi start lai thi cang ton xang va o nhiem moi truong. Vay tiet kiem nang luong o cho nao ? Chang biet thang ngu nao bay ra tro nay lam mat thoi gian nguoi khac. Neu 1 nguoi dung ngay khi bat dau den do thi tat may cung tam duoc, nhung ma 1 nguoi khac dung lai khi sap bat dau den xanh roi cung phai tat may vay thi vai giay sau start lai ha? Chac hok co thang khung nao lam tro do dau.