Experiments of this kind ________ in both the U.S. and Europe long before the Second World War.
| A．conducted | B．was conducted |
| C．had been conducted | D．had conducted |
. The film brought the hours in the village/country to me, ________ I would never forget.
| A．that | B．which | C．when | D．as |
. The flowers now raised here have developed from those ________ in the forest.
| A．once they grew | B．they grew once | C．that once grew | D．once grew |
. Meeting my uncle after all these years was an unforgettable moment, ________ I will always treasure.
| A．that | B．one | C．on which | D．what |
. Society as a whole has a responsibility towards its weaker members, ________ as a result of circumstances they could not control, such as illness and disaster.
| A．people suffered | B．who suffering | C．people who suffered | D．which suffer |
. The thought worried him much ________ he might fail in the exam.
| A．that | B．which | C．when | D．so that |