Tom concluded his lecture ________ that he couldn’t emphasize enough how important our efforts were.
The scientists are studying the effects of human activities______the environment.
The law about banning using thin plastic bags came into_____from 1st Jane this year.
I have offered to work for the store owner _____ one night’s stay.
Tom said he had been working for three hours, _____ ,evidently, was untrue.
---May I use your cellphone?---_____. We are good freinds