In the twentieth century the situation changed and water once more became a vital source of power.
active
necessary
al
【正确答案】 B
【答案解析】 划线词表示“至关重要的”，与very necessary意思相近，故B是正确答案。
Very few people are prepared to sacrifice their own comfort for the good of other people.
up
【正确答案】 D
【答案解析】 划线词表示“牺牲，奉献”，与give up意思一致，故D是正确答案。
She read a poem which depicts the splendor of the sunset.
es
s
bes
ces
【正确答案】 C
【答案解析】 答案选：描述，绘画。describe：描述，形容。declare：宣布。assert：维护。announce：宣布。
