Transcanada is the company constructing keystone .
横加公司是公司建设重点
They 're what ecologists call a " keystone " species , who control the abundance every other species , but require a habitat of sufficient size to support those other creatures .
However , these reserve requirements were abolished by margaret thatcher in 1980 as a keystone in her free market revolution , so that by the late 1980s every control and regulation on city lending had been scrapped .
