The phrase 'has been lengthy process' is correct and usable in written English.
For example, you could write: "Obtaining our work visas for this country has been a lengthy process."
DRS is working with the Federal Aviation Administration and the Homeland Security Department to certify the device for use on commercial airliners, but the process has been lengthy.
The 'fit and proper test' process has been lengthy for King, but he was always adamant that he would be able to take his place as chairman.
If former Democratic congressman Beto O'Rourke, another on-the-fence candidate, has had a public quest — Instagram-living and Medium-posting his way toward a presidential run — then Biden has been quietly agonizing, with a decision-making process that has been lengthier, yet utterly familiar.
It has been a lengthy process that has cost time and money.
"This has been a lengthy process complicated by Tribune's bankruptcy".
Getting it right has been a lengthy process and she was only willing to show the results once she was confident they worked.
However, Obama said the decision to lift the ban was not based on China but on "our desire to complete what has been a lengthy process towards moving toward normalisation with Vietnam".
In September the Briton stated that riding for the team would be like playing football for Manchester United, but ironing out the details of the deal that took him to Britain's flagship squad has been a lengthy process as Wiggins was contracted to race for his Garmin team for 2010, and they were clearly keen to retain his services.
The parents of La Resurrection students came up with the idea for a school nurse and "when we found out they'd asked for this, we thought it would be something good for us to do," he said, adding that coordinating efforts among the parties involved and scheduling the initial trip to Haiti to begin meeting and interviewing candidates has been a lengthy process.
Preparing the archives for scrutiny has been a lengthy process.
