钢件经正火后,提高了钢的()。
A、强度
B、线膨胀系数
C、残余应力
D、延伸率
参考答案:A
如图所示,悬挂的线圈与条形磁铁位于同一平面内,当线圈中通入逆时针方向电流的瞬间,线圈将( )
A.左边向里、右边向外,同时向磁铁靠近
B.左边向外、右边向里,同时远离磁铁
C.左边向外、右边向里,同时向磁铁靠近
D.向磁铁靠近,但不转动
The achievements of the greatest minds in science could never have been reached if it had not been for the patient and accurate work of hundreds of other people.
A.has it not been
B.if it had been
C.if hasn't been
D.had it not been