题目

关于滴瓶中滴管的使用，下列叙述不正确的是（    ） A.向试管中滴加溶液时，滴管尖嘴不要伸入试管口内 B.不能将滴管水平拿持 C.加完药品后应将滴管洗净再放回原滴瓶 D.滴管除了原滴瓶外，不能放在别的地方 答案：思路解析：本题主要考查滴瓶中滴管的正确使用方法。滴瓶中的滴管是专用滴管，使用时应十分小心。滴加液体时，应在容器口垂直悬滴，防止其他试剂玷污滴管，而污染滴瓶中的试剂。在操作过程中，滴管不能手拿、倒置，以防止试剂腐蚀橡胶乳头。用完后，滴管应放回原瓶，不能用水冲洗，否则会阅读下面短文，在短文的空格内填入适当的词，使其内容通顺。（每空格限填一词）               Asking the way in different places     I travel a lot, and I find out different"styles"of giving directions(方向）every time I ask "How can I get to the post office?" In Japan, people use landmarks(地面标志性建筑物）in their directions_1   most streets don't have names. For example, the Japanese will say to travelers,"Go straight ahead and turn left at the hotel. The post office is across from the bus stop." In the countryside of the American Midwest, there are no towns or buildings in many places.Instead of landmarks, people will tell you directions and _2.In Kansas,for example,people will say,"Go north two miles(英里）. Turn east,and then go another mile." People in Los Angeles,California, have 3  idea of distance. They measure(测量）distance in time, not miles."How far away is the post office?" you ask."Oh,"they answer,"it's about five minutes from here." It's true that a person doesn't know the answer sometimes.What _4  in such a situation? A New Yorker might say,"Sorry I don't know." But in Yucatan,Mexico,no one answers"I don't know" People in Yucatan believe that "I don't know" is impolite. They usually give an answer, often a _5 one. A tourist can get very,very lost in Yucatan!