创新题Plants take in carbon dioxide ________ then turn it into oxygen in the air.
A.but B.although C.unless D.and
易错题I'm sorry, ________ I won't be able to come tonight.
A.for B.and C.but D.then
易错题The words “racecar”， “kayak” and “level” are the same ________ they are read left to right or right to left.
A.since B.though C.unless D.whether
(2020原创)I don't have any experience in this task ________ I come here. I am a green hand.
A.if B.unless C.before D.while
(2020原创)I need your help to pick out a shirt for me, the black one ________ the white one?
A.or B.so C.and D.but
(2019河北省保定市莲池区二模)She didn't go to swim ________ she finished her homework.
A.while B.when C.until D.before
