How is the Chinese government trying to prevent democracy from happening in Hong Kong?

The Chinese government is forcing their own type, essentially, of democracy. 2/3rd s of the votes for their "house" is voted for by businesses, which have roots in china and therefore vote the way the Chinese want them to. So, the people only get 1/3rd of the voted in representatives, allowing china to essentially run Hong Kong. This is why the recent protests have been going on, and the passive way china has been resisting democracy in Hong Kong, even though Hong Kong has had huge success.

HK should be able to hold directly election on both the parliament and HK leader by now, but CCP continue refuse to go for it.

CCP insist on setting up an election committee that has the absolute power to deny a person/party from joining the election, this is inherently un-democratic ... People should be able to choose freely who to vote for, the candidates shouldn't need a prior approval from a CCP controlled committee first.