Alice will volunteer to work on the hospital fundraising drive only if her brother Bruce also volunteers and a majority of the others working on the drive promise to select Bruce to manage the drive  However, although Bruce is willing to volunteer, none of the others working on the drive will promise to select Bruce to manage the drive
Thus it is certain that Alice will not volunteer
Leon will go to the picnic only if Vera also goes. However, according to his friends Leon does not plan to go to the picnic: so it is certain that Vera is not planning to go.