This decision could have serious consequences ________ the future of the industry.[ ]

We’ll continue to learn by ourselves when we have left school, we must _______ learn how to study in the school now.

Hardly ______________ when it began to rain

__ have completed his work; otherwise, he wouldn’t be enjoying himself by the seaside.

It was my first time I___________ Chairman Hu,and his speech made a deep impression on me.[ ]