So hard __________ in the past few months that he has made great progress in English–I can see that, only a few mistakes he made in this exam

— Do you know our town well?— Yes, this is the second time that I________here.[ ]

What will people die of in 100 years? If you think that is a simple question, you ______ attention to the revolution taking place in biotechnology

All the scientific evidence ________ that increasing use of chemicals in farming ________ damaging our health.(2012·湖南)

Millie, ______ late for school again. — Sorry, I won’t.