A plane is machine that__flya may b must c can d need顺便说下用法

A plane is machine that__flya may b must c can d need顺便说下用法
A plane is machine that__fly
a may b must c can d need
顺便说下用法

A plane is machine that__flya may b must c can d need顺便说下用法
选c.may是可能的意思.must是必须.can表示能够,need是需要.

C
飞机就是能飞的机器