What mix oxygen in the blood?

haemoglobin

Explanation:

Inside the air sacs, oxygen moves across paper-thin walls to tiny blood vessels called capillaries and into your blood. A protein called haemoglobin in the red blood cells then carries the oxygen around your body.

a-he encouraged islamic schools to introduce greek texts.

d-he invited greek scholars to teach their texts to the locals.

explanation:

the transmission of the greek classics to latin western europe during the middle ages was a key factor in the development of intellectual life in western europe.[1] interest in greek texts and their availability was scarce in the latin west during the earlier middle ages, but as traffic to the east increased so did western scholarship.

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