小鸟在树上唱歌用in 还是用on小鸟在树上唱歌用in 还是用onsome birds are singing ______ the trees.a.in b.on

问题描述:

小鸟在树上唱歌用in 还是用on
小鸟在树上唱歌用in 还是用on
some birds are singing ______ the trees.
a.in b.on