Sarah is _______ a kind-hearted girl _______ she often helps people who are in trouble. [ ]

A. so, that

B. too, to

C. such, that

D. not only, but also

弹性波有各种不同的分类方法，按波源形状及波动在介质中传播的形状，可分为球面波、柱面波和平面波。