单项选择：Planes will be very large ___ flying will be very cheap.A.so B.and C.but
问题描述：
单项选择：Planes will be very large ___ flying will be very cheap.A.so B.and C.but
答
应该是：
选B
前后句是并列关系,所以用and
飞机将会更大,而飞行将会更便宜.
A so 表因果,因此
C but 给转折,但是