Four candidates will vie for three School Committee seats, and a new member will be added to the Board of Selectmen in Tuesday’s annual election. Polls will be open from 7 a.m. to 8 p.m., when voters will also be able to cast ballots for party candidates in the special statewide primary for US Senate. With School Committee member Henry Warren choosing not to seek reelection, the race for the three seats on the ballot features incumbents Helen Charlupski and Susan Wolf Ditkoff, and challengers David Pollak, of Lancaster Terrace, and Laurence Onie, of Marshal Street. Advisory Committee member Neil Wishinsky is running unopposed for a three-year position on the Board of Selectmen; the seat was left vacant when Jesse Mermell stepped down in January to take a job in Governor Deval Patrick’s administration. Three incumbent library trustees — Michael A. Burstein, Jennifer Rees, and Judith A. Vanderkay — are being joined by Puja P. Mehta and Magdalene M. Moran in vying for four seats on the board. A number of precincts also have competitions for Town Meeting seats. Sample ballots have been posted on the town’s website, www.brooklinema.gov .