如图所示所在通电螺丝管内部中间的小磁针,静止时N极指向右端,则电源的c端为_____________极,螺线管的a端为_____________极。
正,S(南)
夏季是用电高峰期,但2013年夏季我国煤炭市场价格依旧弱势运行。造成这一局面的原因可能有( )
①进口煤炭增加 ②国内煤炭行业劳动生产率提高
③国内经济下行压力增大,煤炭需求增长趋缓 ④煤炭的替代商品价格上升
A.①②③
B.②③④
C.①②④
D.①③④
Such good use has been ________ his spare time ________ his English has improved a lot.[ ]
A. made of;as
B. made of;that
C. made in;that
D. made from;as