Titrations
The strength of and acid or base describes the extent to which they ionize/dissociate in solution to produce H+ or OH- ions. For instance, if an acid is strong, it will ionize 100% to produce many H+ ions. If an acid is weak, it will not ionize 100% and produce fewer H+ ions. The same applies to bases.
Thus, when a strong acid is titrated with a weak base, the pH at the equivalence point will be less than 7.
The strong acid will have a pH level that is 1 or below, and the weak base will have a pH level that is between 7 and 10.
The strong acid will drag the pH down.