— I called you at 5:00 yesterday afternoon, but no one answered.
— Sorry, I with my parents _______ at that time.
A:was shopping
B:were shopping
C:are shopping
D:went shopping
已知集合A={1,2,3,4},B={(x,y)|x∈A,y∈A,xy∈A},则集合B的所有真子集的个数为( )
下列哪个物体被托起时所用的力最接近10N( )