--------all the time is key to ------progress in English.

问题描述:

--------all the time is key to ------progress in English.
A practise making B to practise making C practising make D to practise make
选哪个
........ABCD都有了 谁说的对............

B
动词作主语,不适用to do就是用doing的形式,排除A;
key后的to是介词,介词后的动词用doing的形式.