Edison failed _____ times before he succeeded in producing the first electric lamp .

By the time he was 12, Edison _______ to make a living by himself.A.would beginB.has be

Time______, we will do a short presentation before the concert.A．permittedB．permittingC．pe

It was a long time before I could _____ him _____ accepting the job.A.persuade ⋯toB.per

Barbara ______ in doing it again though she had failed more than a dozen times.A.insistedB

I’d met Cynthia several times before this gathering._______.

We won give up ______ we should fail ten times.A.even ifB.sinceC.whetherD.until