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]: Lancelets display all ____ of the vertebrate characteristics throughout their lives.
[A]: four


[Q]: Black widows mature in two to ____ months.
[A]: four


[Q]: Biomedical ethics involves ____ basic principles.
[A]:
two