题干
I want to buy Mother something ______ for her birthday, but I don’t know what she likes best.
A：offered
B：devoted
C：intended
D：contributed
答案(点此获取答案解析）
C
的固定斜面上。滑块与斜面之间的动摩擦因数为
。若滑块与斜面之间的最大静摩擦力合滑动摩擦力大小相等，重力加速度为g，则 （ ）