题目

A professor told his students to go into the city slum(贫民窟) to study the life of 200 boys．He asked them to write reports about each boy’s life and future．Every one of the students wrote，“He doesn’t have any hope．”     Twenty-five years later．another professor read about the earlier study．He told his students to find out what had happened to these boys．Of the 200 boys，20 had moved away or died．Nobody knew what had happened to them．They tried very hard and found the other 180 people．Among them 176 had become successful as doctors，teachers and scie (1)用5.0 mol·L－1的NaOH溶液配制0.1 mol·L－1的NaOH溶液时，下图所示的仪器中，肯定不需要的是________(填序号)，配制上述溶液还需要的玻璃仪器是________(填仪器名称)． (2)在配制过程中，下列操作将导致实际所配NaOH溶液浓度偏低的是________(填编号)． ①准确取出的浓NaOH溶液在空气中露置时间过长；②用量器将浓NaOH溶液直接加入容量瓶，缓慢加入蒸馏水至液面最低点恰好和环形刻度线相切；③摇匀后，液面低于刻度线，再加蒸馏水至液面最低点恰好和环形刻度线相切；④稀释NaOH溶液的仪器未洗涤．