一列火车到站的时刻是10:40,比正常到站晚了30分钟.正常的到站时间是______.
10:40-30=10:10,
答:正常到站时间是10:10.
故答案为:10:10.
如图所示,一自耦变压器(可看做理想变压器)输入端AB间加一正弦式交流电压,在输出端CD间接灯泡和滑动变阻器.转动滑片P可以改变副线圈的匝数,移动滑片Q可以改变接入电路电阻的阻值.则( )
A.只将P顺时针转动,灯泡变亮
B.只将P逆时针转动,灯泡变亮
C.只将Q向上移动,灯泡变亮
D.只将Q向下移动,灯泡变亮
204. Old people think fondly of old times. They often gather and _____ old friend and events.
A.look forward
B.look back on
C.look back
D.look into