import asyncio
import requests


async def download(url):
    print('start')
    await asyncio.sleep(2) # 网络请求，不能用requests.get()
    print('end')


async def main():
    urls = [
        'http://www.baidu.com',
        'http://www.bilibli.com',
        'http://www.163.com'
    ]
    tasks = []
    for url in urls:
        d = download(url)
        tasks.append(tasks)

    await asyncio.wait(d)

if __name__ == '__main__':
    asyncio.run(main())