A:①②
B:②④
C:②③
D:③④
You'd better polish up the o____ version before sending it to the publishing house.
我市校计划购买甲、乙两种树苗共200株来绿化校园,甲种树苗每株25元,乙种树苗每株30元,通过调查了解,甲乙两种树苗成活率分别是90%和95%.