第26题: [单项选择]The survey showed that ______ numbers of 15-year-olds were already smoking twenty cigarettes a week. A. essential B. steady C. primary D. substantial 参考答案:D 答案解析:[解析] 本题中,essential的意思是“本质的”;steady的意思是“稳定的”;primary的意思是“主要的,初步的”;substantial的意思是“大体上,基本上,实质的,坚固的”。四个