— _____

— It's an apartment building.

    Going to work by car is getting more expensive today because the petrol(汽油)is getting more expensive（贵）.People are looking for a cheaper way of transportation and they find out that it is a good choice(选择) to ride bikes to work.More and more return to bikes.

    Children often go to school by bike.But now more people are going to work by bike, too.“The bike is easy to use,”says Molly,“and it is also very cheap. It's a good choice for those who do business（生 意） like me.You can buy thirty bikes for the price of a small car. A bike doesn't use expensive petrol.”

    Mr.Brown goes to his hospital by bike every day. He says,“A bike doesn't cost so much money, and most families can have two or more bikes. Bike riding is good for our health. Today most people get fat because they don't get enough exercise. So I tell all my patients(病人) to buy bikes. Besides, in big cities it's usually quicker to travel by bike than by bus or car. Car drivers can do nothing but get angry when there is a traffic jam（有交通阻塞）.

You should____ ____ ____ ____soon．

植物体的生长发育是从一个细胞开始的，如图表示细胞发生一系列变化的过程，下列相关叙述正确的是（　　）