The law prohibits bidders from colluding with bidders in bidding. Under any of the following circumstances, it belongs to collusion between the tenderer and the bidder, such as the tenderer opening the tender documents before the bid opening and leaking relevant information to other bidders; The tenderee directly or indirectly divulges the pre-tender estimate, members of the bid evaluation committee and other information to the bidders; The tenderer explicitly or implicitly indicates that the bidder reduces or increases the bid price; The tenderer instructs the bidder to replace or modify the bidding documents; The tenderer expressly or implicitly provides convenience for a specific bidder to win the bid; Other collusive acts taken by the tenderee and the bidder in order to seek the bid of a specific bidder.