It is all very well to blame traffic jam, the cost of petrol and the fast pace of modem life, but manners on the roads are becoming ________.
句意：把这一切都归咎于交通堵塞、汽油的价格和现代生活的快节奏，这是再好不过了。但是，交通礼仪正变得越来越糟糕。serious严重的。tempting诱人的。deplorable可悲的、糟糕的。noticeable显著的。因此，本题的正确答案为C。