In order to keep the balance of ecosystem, every possible means _______to deal with the problems of the over-exploiting of natural resources.
| A．has tried | B．has been tried | C．have taken | D．have been taken |
The film brought the hours back to me _______ I was taken good care of in that village.
| A．that | B．where | C．when | D．which |
The mother along with her children _______ in the supermarket when the explosion happened.
| A．was shopping | B．were shopping | C．have been shopping | D．had shopped |
I wish to thank Professor Smith, without _______help I would never have got this far.
| A．who | B．whose | C．whom | D．which |
The problem, according to the experts, is _______ we should do with the salty land.
| A．that | B．how | C．which | D．what |
He has always insisted on _______ Mr. Berg instead of Justin.
| A．been called | B．called | C．calling | D．being called |