It is not decided ________ the conference will be held.
C
A什么B哪一个C什么时候D(无词义)
Theothertimingsystembelongsinourinternalclocks，which，left________，wouldtiethebodytoa25-hourrhythm.
The volunteers would rather go by train than ________.
Countrylifeisbetterthancitylife________itoffersfreshairandnoiselessenvironment