After simplification of any force system in space, a force and a couple are obtained. The magnitude of this force is ( ) the principal vector of the force system. A: equal to B: more than C: less than D: not equal to

If F is a vector field, then divF is a vector field.

In the vector field, the vector line is such a curve where ( ) A: The tangent direction at each point on it is orthogonal to the direction of the vector field at that point. B: The tangent direction at each point on it is parallel to the direction of the vector field at that point. C: The value of each point on it is equal to the value of the vector field at that point. D: The vector line is the geometric curve of the vector field function.

Which of the following statements are correct? A: The greater the modulus, the stiffer the material. B: The stiffer the material, the higher the resistance of the material to deformation. C: The higher the magnitude of elastic modulus, the higher the magnitude of the inter-atomic bonding forces in a material. D: The higher the magnitude of elastic modulus, the lower the magnitude of the intermolecular bonding forces in a material.

下列创建vector容器对象的方法中,错误的是( ) A: vector v(10); B: vector v(10, 1); C: vector v{10, 1}; D: vector v = (10, 1);

The coordinates of a vector relative to a basis in a vector space is unique.

下面哪条语句创建了一个存有10个整数的vector对象？ A: std::vector<int> v(10); B: std::vector v; C: std::vector v[10]; D: std::vector<int> v[10]; E: std::vector(int) v;

The magnitude of a moment is the product of the force and（）.

Which statement as follows is right? A: The potential equals everywhere the magnitude of electric field intensity is equal. B: The magnitude of electric field intensity equals everywhere the potential is equal. C: The potential must be high where the magnitude of electric field intensity is great. D: The potential is not necessarily zero where the magnitude of electric field equals zero.

Any subset of a vector space V which contains the zero vector is a subspace of V.