Given a sentence, fill out the missing word with a 'no' or a number (between zero and ten). You should write the numbers with english alphabet, like: four instead of 4.

Q: Flat screens come in ____ varieties, analog and digital.

A: two
****
Q: Chromatography is unique because of ____ reasons.

A: three
****
Q: Poplars usually are ready for use as biomass energy at ____ years.

A:
five
****