1．scientists are convinced________the positive effect of laughter________physical and mental health. 答案：of; on 解析：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，确信”；effect常与on连用，意为“对……的影响”。以上两个均属于固定搭配。 2．if we are not________ ________(满意) the progress we have made，we will have greater success. 答案：content/satisfied with 解析：句意：如果我们不满足于我们所取得的进步，我们将会取得更大的成功。be content/satisfied with“对……感到满意”。 3．________ ________ ________(一到家) her home，jennifer turned on her computer and chatted on line.(directly) 答案：directly she reached 解析：directly用作从属连词相当于“as soon as”“一……就”，reach为及物动词直接可以跟名词作宾语。
