Which of the following pure liquids contain molecules that can accept a hydrogen bond but have no X-H bond (X = N, O, F) to donate one, so they do not hydrogen bond with themselves?

Acetone has a carbonyl O (acceptor) but no O-H. Trimethylamine has a lone pair on N but no N-H. Dimethyl ether has O lone pairs but no O-H. Methylamine has N-H bonds and a lone pair on N, so it hydrogen bonds with itself and is excluded.