如图所示是某电源的路端电压与电流的关系图象,下面正确的是( )
A:电源的电动势为6.0 V
B:电源的内阻为12Ω
C:电源的短路电流为0.5A
D:电流为0.3A时的外电阻是18Ω
世界上的火山、地震集中分布在地球表面的( )
—The children in rural areas have few books to read. Let's ______ some books to them.—Great, it is a good idea.
______ (T/t)hey were still working in the field ______ it rained heavil.