A.a⊥α and a⊥β B.a⊥γ and β⊥γ C.a are contained in α, B is contained in β, and A is parallel to B.

D.a contains α, B contains α, A is parallel to β, and B is parallel to β.

2. If the straight line A is not perpendicular to the plane α, then the straight line perpendicular to the straight line A in the plane α: (b)

A. there is only one B. there are countless C. all straight lines D. which are plane α do not exist

3. In the cube ABCD-a 1b1c1d1,the angle formed by the straight line A1b and the curved surface ABCD is (b).

30 BC to 45 BC

4. The plane where the square ABCD is located and the plane where the square ABEF is located form a dihedral angle of 60, and the cosine value of the angle formed by the straight line AD and BF is: (c)

A. Two-thirds radical number two B. One-half C. One-quarter radical number two D. One-quarter

5. It is known that the bottom areas of cylinder and cone are equal, and their volumes are V 1 and V2 respectively, so the ratio of V 1 to V2 is (D) A. 1 ratio 3 B. 1 ratio 1 C.2 ratio/d.

6. The following statement is incorrect: (d)

A in space, a set of parallelograms with parallel and equal opposite sides must be parallelograms. B two perpendicular lines on the same plane must be * * * planes. C. When a point intersects a straight line, countless straight lines can be perpendicular to this straight line, and all these straight lines are in the same plane. D when intersecting with a straight line, only one plane is perpendicular to the known plane.

7. In the cube ABCD-A1B1C1D1,the angle formed by the nonplanar straight line AA 1 and BC is (D).

30 BC to 45 BC