A low-carbon lifestyle is of great benefit to improve _____ world environment. Nothing can

be enjoyed from it until you have____ deep understanding of it, though. [ ]

A. a; the

B. /; a

C. the; /

D. the; a

给下列多音字注音并组词。

重 zhòng（　　）chóng（　　）

爪 zhǎo（　　）zhuǎ（　　）

干 gān（　　）gàn（　　）

几 jī（　　）jǐ（　　）