The Communist Party has made great progress in reducing China’s pollution, but     1     perfect storm of northern winds and an industrial rebound has created dangerously high levels of pollution countrywide.

Sandstorms used     2     (be) a regular occurrence in spring. In previous decades, each May saw at least two rounds of sandstorms, according to state-run Xinhua news agency. The     3     (frequent) and severity of sandstorms was partly due to drought,     4     (grow) population pressure and poor progress in revegetation,     5     caused rapid desertification of land in the north and northwest.     6    , sandstorms have since decreased dramatically. The annual number of sandstorm     7     (impact) days in Beijing fell from a peak of 26 in the 1950s to just three days after 2010, Xinhua reported.

Since 2000, the Chinese government     8    (invest) billions of dollars toward sandstorm prevention. Authorities have launched     9     (variety) reforestation and ecological projects, and installed satellites to monitor sandstorms and alert weather agencies     10     of time.