Birds have air sacs and lungs. When birds breathe (in / out,) oxygen-rich air fills the
lungs and air sacs. When birds breathe
(in / out), the oxygen-poor air leaves the
lungs, and stored fresh air enters the lungs from
the air sacs. This means that birds always have a
supply of oxygen-(rich / poor) air.

Acar traveld with an average speed of 60 miles per hour for 2 hours. how far did it travel

Will mark brainliest if correct/available! which of the following statements is true? all plants need flowers to sexually reproduce. sexually reproduced offspring are identical to their parents. fertilization always occurs inside the female's body. a body cell has twice the number of chromosomes as an egg cell.

20 points and brainlist 1. london has suffered from terrible air pollution for at least seven centuries. why is the city so prone to its famous “london fog? ” what did london do to get rid of its air pollution? 2. why does air pollution cause problems in developing nations more than in developed ones?