根据下列各句意思及所给单词的首字母或汉语提示，写出该单词的正确形式。
小题1:I hope this summer holiday will be _____________(有益的) to your study.
小题2:He was the only _____________( 目击者) of the accident, who would give important information.
小题3:Statistics _____________(表明) that the world population has doubled.
小题4:Tom was ___________(推选) chairman, for he is hardworking and responsible.
小题5:Can you _____________(推荐) a good dictionary to me ?
小题6:I wonder if you’ll c_________________ them all on their success.
小题7:She had a strong d_______ to go abroad for further study.
小题8:He was a_________ of wind in his face.
小题9:All the students p_______________ in cleaning the street.
小题10:He o________ his success to the good education he received.
