Read the passage and choose the correct answer A, B, C, or D. Not long ago, open-air markets played an important part in the lives of the Vietnamese. Wherever there was open space, the local people could start their own market. There, you could find almost everything from local home-made and home-grown products to those that the sellers bought wholesale from somewhere and resold them for a profit. Since the locals went there nearly every day, they knew one another, and the sellers even ...

Read the passage and choose the correct answer A, B, C, or D.

Not long ago, open-air markets played an important part in the lives of the Vietnamese. Wherever there was open space, the local people could start their own market. There, you could find almost everything from local home-made and home-grown products to those that the sellers bought wholesale from somewhere and resold them for a profit. Since the locals went there nearly every day, they knew one another, and the sellers even remembered the customers’ preferences.

Then supermarkets came and soon became popular. There are many reasons to explain their popularity. First, they offer a cool and large shopping site. Shoppers can spend hours in them without worrying about heat or rain. Second, they provide shoppers with a wide range of goods, from foods and kitchenware to cosmetics and pet care products. People do not have to move from shop to shop to collect all the things they need. Nowadays, many supermarkets even offer home delivery service and online shopping, which makes shopping even easier.

In the past, the local people could start an open-air market when _______.