_______ is known to all，China will be an _______ powerful country in 20 or 30 years’ time.
C
as可以用来引导一个非限制性定语从句，通常无明显的先行词。as指代的是主句陈述的内容。而as引导的从句既可以放于句首，也可以放于句末或句中。
_______ in thought, he almost ran into the car in front of him.
A man flown to a time zone different by 10 hours will ________ eight days to readjust his palm sweat.
You’ll be there tomorrow -- you won’t ________ me ________, will you ?
People appreciate _______ with him because he is knowledgeable and humorous.