（1）下列各组物质均由分子组成的是　 ____　

①金刚石、氨气、氧气

②二氧化碳、二氧化硅、二氧化硫

③空气、冰、碘蒸气

④液氯、液氨、熔化的食盐

（2）直接由原子构成的是　 ____　．

①二氧化硅   ②二氧化碳   ③钠   ④金刚石   ⑤单晶硅

⑥白磷   ⑦硫   ⑧氨气  ⑨溴化氢   ⑩碘蒸气．

    There are many different ways to travel to Paris from London. One of the quickest and most popular ways is by train. From Waterloo Railway station, you can travel all the way to Paris. The journey takes about three hours. The train, called the Eurostar, is very modern, and the seats are comfortable.
    You can also travel to France by ship. First, you go to Dover, on the coast (海岸), by bus from London. The bus stops at the Ferry Terminal Seven in Dover. You can buy your tickets there. People who travel by car can drive on to the ferry (渡轮), too.
Another way to travel to Paris is by plane. There are several airports with international flights to Paris and other cities in France. You can travel to London Airport by bus or underground. Some people even go by taxi but this is a very expensive way to travel!