_____ your son has no interest in piano ,there is no point pushing him to learn it.

A Now that   B So that     C Even if     D As if

读“地震波波速变化图”，回答题。

关于古登堡面上波速变化的叙述，正确的是（）

A.横波完全消失，纵波波速突然下降

B.横波、纵波波速明显增加

C.横波消失，纵波波速明显增加

D.横波明显降低，纵波完全消失