Some plants can take in carbon dioxide we breathe out and give oxygen to us.
A. in case
B. in turn
C. in return
D. in addition
网友回答
A. in case
B. in turn
(答案→)C. in return
D. in addition
解析：介词短语辨析。A以防；B依次，轮流；反过来；C作为回报；D另外；结合句意可知C正确。句意：一些植物能够吸收我们呼出的二氧化碳，作为回报并给我们氧气。