Cho tam giác ABC. Hỏi có bao nhiêu điểm M sao cho vectơ tổng M A →   +   M B →   +   M C → có độ dài bằng 3?

A. Có duy nhất một điểm

B. Có hai điểm

C. Có vô số điểm và tập hợp các điểm M là một đường thẳng

D. Có vô số điểm và tập hợp các điểm M là một đường tròn

Read the following passage carefully, and then select the best option A, B, C or D to complete it

Music, artful arrangement of sounds (1) _______ time. This definition is obviously very broad, but a narrower one would exclude (2) _______ much. Music is part of virtually every culture on (3) _______, but it varies widely among cultures in style and structure. Definitions of music can (4) _______ dramatically over a short time, as they have across the world during the 20th (5) _________.

Can music exist without (6) _______? Some philosophers argue that music should be defined as a kind of “mental (7) _______” and that the physical aspects of sound are simply by-products of this image. If you (8) _______ you can have a musical experience by imagining the sound of a piece of music, then you think (9) _______ can exist without sound. But most musical experiences involve producing or (10) _______ to physical characteristics of sound such as pitch and timbre (quality comparable to texture or color in sight).

Is the tape-recorded sound of a large metal-stamping machine music? Are 4 minutes (11) _______ 33 seconds of silence music? Is the activity of reading a (12) _______ of hundreds of seemingly unrelated objects, activities, and states of mind music? Each of these “(13) _______”, as well as many other sounds (or nonsounds), has been copyrighted (14) _______ a musical composition, performed, and recorded in the 20th century. One of the legacies of 20th-century music is to have blurred the definition of music as (15) _______ before.

Question 31:

A. and

B. but

C. or

D. so

Cho tam giác ABC. Gọi M là điểm trên cạnh BC sao cho MB = 4MC. Khi đó biểu diễn A M → theo A B →   và A C →   là:

A.  A M →   =   4 5 A B →   -   1 5 A C →

B.  A M →   =   4 5 A B →   +   A C →

C.  A M →   =   4 5 A B →   +   1 5 A C →

D.  A M →   =   4 A B →   +   A C →

He _______ the girl on the arm to get her attention.

A. touched

B. touches

C. to touch

D. touching