In today’s fast changing and competitive world, to be able to learn faster and more effectively is not merely desirable; it is ________.

Did he come back late last night? —No．It was not yet eight o’clock _____________ he arrived home

There are __________ oranges onthe table. the three

aware of the__________ofthe disaster, some famous stars organized a charity concert to raise money forthe victims.

_____, I was afraid of the dark, then I went to bed withmy bedroom light ____.