考博考试

【单选题】 The survey showed that ______ numbers of 15-year-olds were already smoking twenty cigarettes a week.
A．essential
B．steady
C．primary
D．substantial

网考网参考答案：D
网考网解析：
essential本质的；steady稳定的；Primary主要的，初步的；substantial大体上，基本上，实质的，坚固的。 查看试题解析出处>>