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.

Lancelets display all ____ of the vertebrate characteristics throughout their lives.
four

Avian kidneys have ____ kinds of nephrons.
two

Skunks tear out divots of turf that are three to ____ inches in diameter.

six