I will never forget the day____ we spent in the old town with small houses.
A:who
B:whom
C:that
D:what
下列四幅地貌景观图中,因侵蚀作用而形成的地貌是
已知a→=(λ+1,0,2),b→=(6,2μ﹣1,2λ),若a→∥b→,则λ与μ的值是____