1.absent-minded,he went to school on sunday,______it was monday.
a.thought b.thinking c.while thinking d.to think
2.the result of the contest was not made____to the public until yesterday.
a.knowing b.known c.to know d.to be known
3.___,so i had to wait for my parents back.
a.because my key was lost b.my key was lost
c.losing my key d.having lost my key