How do you understand the“first half”of a month according to the terms of shipment in the contracts( )
A．the 1<sup>st</sup> to the 10<sup>th</sup> B．the 1<sup>st</sup> to the 15<sup>th</sup> C．the 11<sup>th</sup> to the 20<sup>th</sup> D．the 21<sup>st</sup> to the last day of the month