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: Sexual maturity occurs at ____ to four years for females and four to five years for males.

A: three
****
Q: Norplant implants are ____ matchstick size rods that are inserted into the upper arm.

A: six
****
Q: Whales are thought to sleep around ____ hours a day .

A:
eight
****