QUES: Often families sold some of their young children to survive

correct the punctuation.

CORRECTED: Often families sold some of their young children to survive.

QUES: 42Your teeth are like a newly shorn flock which have come up from the washing where every one of them has twins

correct the punctuation.

CORRECTED: 4:2Your teeth are like a newly shorn flock, which have come up from the washing, where every one of them has twins.

QUES: Leukemia is a cancer of the blood and bone marrow

correct the punctuation.

CORRECTED:
Leukemia is a cancer of the blood and bone marrow.