What country is Pittsburgh in?

Pittsburgh, located in the northeastern United States, is an ancient industrial city in Pennsylvania and the earliest steel base in the United States. Due to the rise of other steel cities, the steel industry here has also shifted to other cities. There are three big rivers in downtown Pittsburgh, 28 bridges with different styles connect the ancient city, and hundreds of expressways (many of which are expressways) run through every corner of the city like cobwebs, so the traffic is very convenient. Because it is located in the hilly area, it is difficult to tell the direction except for a few straight roads in the city center, which are all forks in the road. An American young man who came to Pittsburgh from Ohio to go to college told us (he is a language major and can speak Chinese) that he said, "The terrain in Pittsburgh is too complicated. I wanted to go east by car, but I changed direction when I walked. " We feel the same way. On Sunday, my daughter took us shopping in the city center, and we kept going up and down, beating around the bush. There are many road signs and traffic lights, and there is no traffic police at the intersection, so we rely on traffic lights to guide us. Americans have a strong sense of driving safety. It is better to wait for three minutes than to grab a second. Politeness is the purpose of every driver's action. In addition, all kinds of vehicles have to give way to pedestrians, which is stipulated by law, so there are fewer traffic accidents in the United States. Similarly, pedestrians obey the traffic laws very much, and don't cross the road until they see the green light. Everyone is very conscious and feels safe walking on the road. Pittsburgh is an ancient city, which existed 227 years ago before the independence of the United States. The natural virgin forest embraces the ancient city and the green ocean. Because it is located in the hilly area, it takes less than ten minutes to drive to the suburbs, and there will be dense forests and continuous mountains, and no one will be there. It won't be long before you can see high and low buildings in the dense forest. Some houses look inclined, but in fact they are straight. The orientation of the house is very distinctive, and there are few houses due south, north, east and west. Because of the terrain, we can only adapt to local conditions and face to face. Private houses do not exceed three floors, usually two or three floors. If there is an apartment, there are seven or eight floors and a dozen floors. There is a highland park not far from my residence. The main entrance and exit of the park is Highland Avenue leading to the city center. American parks do not need to buy tickets, and they are free to enter and leave. This is a park transformed from virgin forest. There are thousands of towering trees in the park with different shapes and ages, and there are also new trees planted after the founding of the People's Republic of China. Some old trees have experienced vicissitudes of life, and there are holes in the bottom, but the upper parts are still flourishing. Nature nourishes their descendants, full of vitality and prosperity. The tall and stout ginkgo tree, full of fruits, bent its branches. Male ginkgo trees do not bear fruit. It stood there in a heroic manner, watching its lover bear the burden of humiliation, and it could do nothing. Growing up in the city, I saw chestnut trees for the first time in my life. Chestnuts in Hebei Province of China are famous all over the country for their large size, and chestnuts in Pittsburgh are no less than it. Chestnut tree is not as tall as ginkgo tree, but it is more than ten meters long, and the fruit can't be reached by hand. In her spare time, my daughter drives a car, ties hooks with bamboo poles, and hooks the fruits one by one. It takes clips to put them into plastic bags, because the round shell is covered with hard needles and there are two or three nuts in the fruit, which is the real chestnut. It is true that the ancients said, "It is never too old to learn". March and April in early spring are really the season of flowers. The buds of all kinds of fruits are in bud, and in a few days, all love is full of colors, forming a colorful world. The spring breeze blows waves of rich floral fragrance, which makes people feel relaxed and happy. All kinds of birds are flying in the air. There are many kinds of birds in America with different colors, some with light blue feathers, some with a tuft of hair on their orange heads, which I call crested birds, and some small sparrows with special flying skills. No pollution, no noise, fresh air, quiet environment and blue sky. White clouds are floating there. On the green grass, wild pigeons are foraging, and birds are chirping in the branches when they are tired of flying. This song is so beautiful, sweet and pleasant to listen to, as if welcoming China "foreigners" from the other side of the ocean. This situation makes me get carried away, and I really want to shout: Nature, you are so beautiful. In the middle of the park, three meters from the ground, there is a large reservoir with a circumference of about three kilometers. It takes about 25 minutes to turn around, and the water quality is crystal clear. Every evening, three or five groups of wild ducks fly from afar to live here. After dawn, they leave the water and fly to the grass to play, love and breed. One day in mid-April, I suddenly found a nest of six ducklings playing on the water with their mothers. These ducklings are very small, as if they have just hatched. These ducklings form another landscape in the park. Tourists linger, and the biggest mystery is how these little things come from. They haven't wings yet, and they can't fly at all. How did mother duck move them here? In the later days, they never left the reservoir. At that time, the weather was still very cold. At night, mother duck took them to the steps near the reservoir, covered their weak bodies with two wings, and preferred to catch cold alone. Usually, she always follows the children. When she meets intruders, Mother Duck rushes to disperse them to protect the safety of ducklings. I didn't expect a bird to have such a great maternal love. These little things are really worrying. I usually feed them bread crumbs. As long as you are near the water, the clever duckling will swim to you to show friendly welcome and thanks. By the time I left Pittsburgh, the ducklings had grown into "people". Like their mother, they left the water in the morning and flew in the blue sky.