Massive floods have hit several provinces along China’s Yangtze River, where rainfall in the middle and lower reaches of the waterway has hit the second-highest levels recorded during the July 1 to 7 period since 1961. Extreme weather across the country has also forced some areas to postpone all-important national college entrance exams known as gaokao. A key reservoir in the eastern province of Zhejiang has opened all nine of its spillways for the first time after flood-control levels were…