The children ＿＿＿＿＿＿ very quiet； I wonder what they ＿＿＿＿up to.
| A．were； are being | B．are being； are | C．are； do | D．are being； do |
Before traveling in space, you must know what it might feel like_____in an imaginary environment.
| A．to travel | B．traveling | C．to be traveling | D．travel |
She's really _____ yoga these days - she does three classes a week.
| A．going into | B．getting into | C．running into | D．looking into |
Since you can solve the problem,I don’t feel_____worthwhile taking such trouble.
| A．that | B．me | C．that | D．it |
The scientists are studying the effects of human activities______the environment.
| A．in | B．at | C．on | D．with |
The law about banning using thin plastic bags came into_____from 1st Jane this year.
| A．existence | B．power | C．sight | D．effect |