Jim______ sing Chinese songs very well now, but he______do it last year.
A:can; can't
B:could; can't
C:can; couldn't
D:could; couldn't
有的小商贩为了吸引买主,用高音喇叭反复播放提示语,噪音干扰了人们逛街、购物的秩序和心情,引起了人们的不满。这一事实告诉我们( )
下列说法正确的是( )