As only few than half the parents took part in the ballot, the vote was declared invalid.

由于只有不到一半的家长参加了投票，所以它被宣布为无效的。

youdao

But the U.N.-backed Electoral Complaints Commission examined more than 2,500 allegations of fraud including phantom polling stations, ballot-stuffing and police intimidation and declared a third of Mr.Karzai's ballots invalid, reversing his outright victory.

VOA: standard.2009.10.20

If a majority opts for this odd feature of the Russian ballot paper, the poll becomes invalid.

ECONOMIST: A Russian coronation | The

In a statement declaring the doctorate invalid and withdrawing it from Ms Schavan, the faculty head Bruno Bleckmann said they had "decided by secret ballot, by 12 votes to two, with one abstention".

BBC: German minister Annette Schavan quits over 'plagiarism'