问题
单项选择题
水下混凝土灌注时间不得长于首批混凝土（）。
A．终凝时间
B．初凝时间
C．拌和时间
D．施工时间
答案
参考答案：B
搜题请搜索小程序“爱下问搜题”
水下混凝土灌注时间不得长于首批混凝土（）。
A．终凝时间
B．初凝时间
C．拌和时间
D．施工时间
参考答案：B
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| Big schoolbags have been a serious problem for students for a long time.Maybe your schoolbag is too __26__ to carry, and it troubles you a lot __27__ you want to find a book out to read. Now an etextbook will __28__ you. It is said that etextbooks are going to be __29__ in Chinese middle schools.An etextbook, in fact, is a small __30__ for students.It is much __31__ than a usual schoolbag and easy to carry. Though it is as small as a book, it can __32__ all the materials (材料) for study.The students can read the text page by page on the __33__， take notes with the pointer (屏写笔). Or even “__34__” their homework to their teachers by sending emails. All they have to do is to press a button. Some people say etextbooks are good, but some say they may be __35__ for the students' eyes. What do you think of it? | ||||
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