皮皮学，免费搜题
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【单选题】
发现并将细胞命名为“CELL”的学者是A.
R.Hook
B.
M.Schileiden
C.
T.Schwann
D.
R.Virchow
E.
R.Remak
拍照语音搜题，微信中搜索"皮皮学"使用
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知识点：
皮皮学刷刷变学霸
举一反三
【单选题】If the contacts of a motor starter or controller fail to drop out when the 'stop' button is depressed the _____.
A.
contacts are carrying excessive current
B.
contacts have become welded together
C.
shading coil is broken
D.
shading coil is loose
【单选题】竖向土方、山坡切土,开挖深度应按基础垫层底表面标高至交付施工场地标高确定,无交付施工场地标高时,应按( )标高确定。
A.
垂直地面
B.
自然地面
C.
水平地面
D.
地坪
【单选题】以下定义的4个视图中，能够进行更新操作的是_________。
A.
CREATE VIEW S_G(学号,姓名,课程名,分数) AS SELECT S.学号,姓名,课程名,分数 FROM student S,score SC,course C WHERE S.学号=SC. 学号AND SC. 课程号 = C. 课程号
B.
CREATE VIEW S_AVG(学号,平均分) AS SELECT 学号,AVG(分数) FROM score WHERE 分数IS NOT NULL GROUP BY 学号
C.
CREATE VIEW S_MALE(学号,姓名) AS SELECT 学号,姓名 FROM student WHERE 班号='09031'
D.
CREATE VIEW S_FEMALE(姓名,出生日期) AS SELECT 姓名,出生日期 FROM student WHERE 性别='女'
【单选题】Motor controller or starter contacts may become pitted and welded together if the contacts _____.
A.
open under loaded conditions
B.
close slowly with light pressure
C.
open too quickly and arc
D.
close quickly with proportionate pressure
【单选题】在党的八大上所做的发言中，陈云提出了（）的重要意见，受到重视，为大会决议所采纳。这是探索我国经济体制改革的尝试。
A.
既反保守，又反冒进
B.
给地方和企业适当下放权力
C.
“三个主体，三个补充”
【单选题】Motor starter or controller contacts may become welded together if the contacts ( )
A.
open too quickly and arc
B.
close under excessive pressure
C.
open or close too quickly
D.
close under excessive starting current
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