In Australia, surfing is a popular sport among young people ____ they can seek excitement

and adventure.[ ]

A. that

B. which

C. where

D. how

重量G=100N的物体置于水平面上，给物体施加一个与水平方向成θ=30°的拉力F，F=20N，物体仍处于静止状态，求：地面对物体的静摩擦力和支持力。