1. If the bidder modifies or withdraws the bid after submitting the bid, the buyer must receive a written notice of modification, including replacement or withdrawal, before the specified deadline for bidding.

2. The bidder's notice of modification or withdrawal shall be prepared, sealed, marked and sent according to Article 18. The notice of bid withdrawal shall be sent by telegram and then confirmed by signed letter, and the postmark shall not be later than the deadline for bidding.

3. After the deadline for submission of bids, the bidder shall not make any modification to its bid.

4. From the deadline of bidding to the deadline of bid validity determined by the bidder in the format of bid letter, the bidder shall not withdraw its bid, and its bid bond will be confiscated according to the provisions of Article 15.7 of the Instructions to Bidders.