一游客在乘缆车匀速上山的过程中,他的动能 _________ ,重力势能 _________ ,机械能 _________ .(填“增大”、“减小”或“不变”)
不变;增大;增大
Although there are different _______ of transportation in this area, the fastest _______ to walk. [ ]
A. means, are
B. mean, is
C. means, is
D. mean, are
有些情况下,对外发生经营业务收取款项时由付款方向收款方开具发票。( )