The partner of rookie cop Peter Liang told Brooklyn jurors Thursday that he himself was unqualified to resuscitate the man Liang accidently shot in a housing-project stairwell — because the Police Academy lets ­recruits cheat on their CPR- certification tests.

So he did nothing to help the dying victim.

“How much time [during training] did you spend on a mannequin?” the partner, Shaun Landau, was asked by Liang’s defense lawyer, ­Robert E. Brown.

“Not sure,” Landau ad­mitted.

“Less than two minutes?” the lawyer asked.

“Yes,” Landau answered.

Jurors learned Thursday that nothing could have saved unarmed Akai Gurley from the bullet that ricocheted off a stairwell wall and pierced his heart, killing him in minutes.

Still, both Landau and ­Liang failed to try to resuscitate the 28-year-old Gurley as he bled to death in East New York’s Pink Houses in November 2014, instead leaving his hysterical girlfriend to do chest compressions, jurors were told.

“But you’re certified in CPR?” Brown asked Landau.

“Yes,” the partner answered nervously.

“And at that moment you didn’t know what to do?”

“Yes,” Landau answered.

Landau, the star prosecution witness, who testified against his partner under an immunity deal, could wind up helping Liang.

Landau said the NYPD’s CPR training was so lax, ­instructors handed out the questions and answers in advance of the written certification exam.

“You were fed the questions and the answers?” Brown asked. “Correct,” Landau replied.

A defense witness, Officer John Funk, later backed Landau’s claim, telling jurors CPR training was equally lacking when he and Liang attended the same 2013 academy class. Some 300 ­recruits crowded into an auditorium with just eight mannequins, and everyone passed, Funk said.

The NYPD did not ­respond to requests for comment.

The prosecution wrapped its case Thursday with radio and 911 time-stamp testimony supporting its contention that the partners wasted at least five minutes bickering over what to do before summoning help.

Landau testified Tuesday that he and Liang didn’t know for at least four minutes that the bullet had struck anyone.

Liang, 27, is charged with six counts, including manslaughter.

Additional reporting by Shawn Cohen and Laura Italiano