链杆对它所约束的物体的约束力(),作用在物体上
A. 垂直于支承面
B. 沿着链杆方向,指向不定
C. 沿着杆轴线方向,且指向被约束的物体
D. 沿着链杆轴线方向,且背离被约束物体
Jae-Hyuk had to _______out at 7:30 in the morning to go to college.
A. hurry
B. concentrate
C. hang out
D. wonder
Jae-Hyuk goes to the club room to ___________with his friends.
A. hurry
B. wonder
C. hang out
D. concentrate