题目

根据短文内容及首字母提示，填写所缺单词，使短文意思完整。 Have you had a headache during a test? Have you ever been so worried about something t _   101 you have a headache or even can’t sleep at night? If s_______102, then you know what stress is. Stress is what you f________103 when you are worried about something. This worry in your mind can make your body feel bad. You may feel angry, sad, scared, or afraid. All of them can give you a stomach or a headache.     However, there are different kinds of stress. Some kinds of stress are good and o_______工业纯碱中常常含有NaCl、Na2SO4等杂质．为测定某工业纯碱的纯度，设计了如图实验装置．依据实验设计，请回答：（1）装置中盛装稀硫酸的仪器名称是 ； 装置D的作用是 ．（2）为达到实验目的，一次实验中至少应进行称量操作的次数为 ．（3）若不考虑操作、药品及其用量等方面的影响，该实验测得结果会 （填“偏高”、“偏低”、“无影响”）；原因是 （你若认为无影响，该空不用回答）．