根据下列句子的意思及所给的汉语提示，写出空缺处单词、固定短语或固定搭配的正确形式。

小题1: Betty is a good friend of m________. We often help each other.

小题2:They have invited a_________(science) to give them a speech on space.

小题3:Mrs. Chan told us to write as_________(care) as we could.

小题4: We Chinese sometimes__________(借) words from English when talking.

小题5:Victor__________(敲) the door before he walked into the room.

配电装置中，相邻带电导体的额定电压不同时，其间的最小距离应按下列哪些条件确定？（）

A.按较高额定电压的A2值确定

B.按较高额定电压的D值确定

C.按较低额定电压的A2值确定

D.按较低额定电压的B1值确定