I can never forget the days _____ we worked together and the days _____ we spent together.A. when; which B. which; when C. what; that D when; when
Before traveling in space, you must know what it might feel like_____in an imaginary environment.
She's really _____ yoga these days - she does three classes a week.
Since you can solve the problem,I don’t feel_____worthwhile taking such trouble.
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.