必修2 unit 1 tales of the unexplained 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“对……的影响”，固定搭配。] 2．they are against the proposal，for it ________too much farmland. a．puts up b．takes up c．gives up d．makes up
