Given two noun phrases (arguments) and relationship between them, form a sentence that expresses theses arguments with the given relationship.

Relationship: 'be head of', Argument/Subject 1: 'president', Argument/Subject 2: 'executive'
The service has been dubbed Derivatives Collateral Net and automatically aggregates and nets the overall collateral obligations of its participants , explains Art Certosimo , executive vice president and head of Broker-Dealer Services at the bank .

Relationship: 'begin in', Argument/Subject 1: 'game', Argument/Subject 2: 'january'
Games will begin the week of February 16th.Packets will be available January 14th in the Maintenance Trailer .

Relationship: 'speak for', Argument/Subject 1: 'aaron', Argument/Subject 2: 'mose'

4:29And Moses and Aaron went and gathered together all the elders of the children of Israel : 4:30And Aaron spake all the words which the LORD had spoken unto Moses , and did the signs in the sight of the people .