Without the friction (摩擦力) between feet and the ground, people would ______ be able to walk.

A．in no time

B．by all means

C．on any account

D．in no way

丹霞地貌又称红层地貌，是指在巨厚的红色沙砾岩上发育的方山、奇峰、岩洞、赤壁等特殊地貌，具有较高的旅游价值。