皮皮学，免费搜题
登录
搜题
【单选题】
用百分表测量时，测量杆应预先压缩0.3～1 mm，以保证有一定的初始测力，以免（ ）测不出来。A.
尺寸
B.
公差
C.
形状公差
D.
负偏差
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【简答题】涂料防水层施工，可以采用______或______两种方法。
【单选题】Not until his mother came back_______.
A.
he began to do his homework
B.
had he began to do his homework
C.
he had begun to do his homework
D.
did he begin to do his homework
【简答题】He was told under no circumstances ______ the computer. A) he may use B) he use may C) may he use D) may use
【单选题】He stepped into the office ， down and began to fill in the forms ．
A.
． sitting
B.
． to sit
C.
． sat
D.
． having sat
【单选题】下列说法正确的是 ___ ___
A.
改变激发光波长，荧光发射光谱的形状随之改变
B.
芳香族化合物分子中， π 电子共轭程度越大，荧光越易发生，荧光光谱向短波移动
C.
同一种荧光物质在不同溶剂中荧光发射光谱不会发生变化
D.
实验证明多数具有刚性平面结构的有机物分子具有强烈荧光
【简答题】He began his career in 198
【简答题】He began to use bright colours in his paintings, especially the ______ and _______ for which he is known, after about ________.
【简答题】分子的共平面性越大, π 电子共轭程度越高,分子的荧光效率也 ,因此荧光光谱将向 方向移动。
相关题目：