江苏省溧阳市2015
高考英语单项选择训练（4）及答案江苏省2015高考英语一轮课时作业及解析04 ⅰ.单项填空 1．scientists are convinced ________the positive effect of laughter ________physical and mental health. a．of；at b．by；in c．of；on d．on；at 答案 c [句意：科学家们坚信笑对身心健康有积极影响。be convinced of坚信，深信；effect常与on连用，意为
