题目

语法填空Robert, a great golf player, once won a tournament. After    (receive) the check, he walked a lot to his car in the parking lot and    (approach) by a young woman.She congratulated him   his victory and then told him that her child was   (serious) ill and near death. She did not know how she could pay the doctor's bills. Touched by    (she) story, Robert gave the check to the woman.The next week he    have) lunch in a restaurant when a Professional Golf Association official came to his table. 由Na2O、Na2O2、Na2CO3、NaHCO3、NaCl中的某几种组成的混合物，加入盐酸放出的气体通过过量NaOH溶液后，气体体积有所减小。将上述混合物在空气中充分加热，有气体放出，且残留固体质量有所增加。由此可知混合物中一定含有_________，不能确定是否含有_______。