Thanks to the Internet, different kinds of information _______ in a short time.
A:can be learned
B:has been learned
C:can learn
D:has learned
关于男女同学之间如何交往,下列说法正确的是( )
— I think buyers ________ spend too much time going to shops.
设a→,b→是两个不共线的非零向量,则“向量a→-λb→与λa→-4b→共线”是“λ=2”的( )