下列几种情况中,物体的势能发生变化的一组是
①跳伞运动员匀速降落;②钢锯条逐渐弯曲;③吊扇匀速转动;④汽车在水平路面上加速行驶[ ]
A.①②
B.②③
C.①④
D.③④
答案:A
I can ________ swim _______ skate. Will you please teach me?
A.either…or
B.not only… but also
C.both… and
D.neither… nor
脉为()
A.元神之府
B.玄府
C.血之府
D.孤府
E.传导之府