【名词&注释】
机械唯物主义(mechanicalmaterialism)、富兰克林(franklin)、朴素唯物主义(naive materialism)、客观唯心主义(objective idealism)、动名词(gerund)、主观唯心主义(subjective idealism)
[单选题]Franklin ______ learning astronomy at an early age.
A. set about
B. set out
C. set off
D. set up