In our city there are more and more cars and buses on the roads. Many people drive to work .First, it's good to have a car. You needn't to wait for the bus. You can go to work on time. Then ,there are many busy roads in the city . Can you drive safely? Traffic lights are very important. You must look at the traffic lights and wait for the green man. If someone is crossing the road, you must stop your car and look carefully. We must follow the rules and stay safe on the road.

阿莫西林是一种常见的抗生素，其化学式为C₁₆H₁₉N₃O₅S，关于阿莫西林的说法正确的是（　　）

一个三角形的三个内角之比是1：2：3，这个三角形三个内角各是多少度？

改正下列各句中的错别字。

①蹑手蹑脚       悴不及防       怡然自得       沾亲带故____

②气息奄奄       消声匿迹       巧妙绝伦       情郁于中____