Nguyên nhân chủ yếu dẫn đến những cuộc xung đột vũ trang trong thời kì sau Chiến tranh lạnh là

Giả sử số tự nhiên thỏa mãn . Khẳng định nào sau đây là đúng?  

Question 24: The author mentions Vivaldi and Tartini in passage as examples of composers whose music___________.    

Of all modern instruments, the violin is apparently one of the simplest. It consist in essence of a hollow, varnished wooden sound box, or resonator, and a long neck covered with a fingerboard, along which four strings are stretched at high tension. The beauty of design, shape, and decoration is no accident, the proportions of the instrument are determined entirely by acoustical considerations. Its simplicity of appearance is deceptive. About 70 parts are involved in the construction of a violin. Its tone and its outstanding range of expressiveness make it an ideal solo instrument. No less important, however, is its role as an orchestral and chamber instrument. In combination with the larger and deeper-sounding members of the same family, the violins form the nucleus of the modem symphony orchestra. The violin has been in existence since about 1550. Its importance as an instrument in its own right dates from the early 1600’s, when it first became standard in Italian opera orchestras. Its stature as an orchestral instrument was raised further when in 1626 Louis XIII of France established at his court the orchestra known as Les vinq-quatre violons du Roy (The King's 24 Violins), which was to become widely famous later in the century. In its early history, the violin had a dull and rather quiet tone resulting from the fact that the strings were thick and were attached to the body of the instrument very loosely. During the eighteenth and nineteenth century exciting technical changes were inspired by such composer-violinists as Vivaldi and Tartini. Their instrumental compositions demanded a fuller, clearer, and more brilliant tone that was produced by using thinner strings and a far higher string tension. Small changes had to be made to the violin's internal structure and to the fingerboard so that they could withstand the extra strain. Accordingly, a higher standard of performance was achieved, in terms of both facility and interpretation. Left-hand technique was considerably elaborated, and new fingering patterns on the fingerboard were developed for very high notes.

Công thức tính số tổ hợp là:

Question 23: The word “they” in the passage refers to___________.         

Of all modern instruments, the violin is apparently one of the simplest. It consist in essence of a hollow, varnished wooden sound box, or resonator, and a long neck covered with a fingerboard, along which four strings are stretched at high tension. The beauty of design, shape, and decoration is no accident, the proportions of the instrument are determined entirely by acoustical considerations. Its simplicity of appearance is deceptive. About 70 parts are involved in the construction of a violin. Its tone and its outstanding range of expressiveness make it an ideal solo instrument. No less important, however, is its role as an orchestral and chamber instrument. In combination with the larger and deeper-sounding members of the same family, the violins form the nucleus of the modem symphony orchestra. The violin has been in existence since about 1550. Its importance as an instrument in its own right dates from the early 1600’s, when it first became standard in Italian opera orchestras. Its stature as an orchestral instrument was raised further when in 1626 Louis XIII of France established at his court the orchestra known as Les vinq-quatre violons du Roy (The King's 24 Violins), which was to become widely famous later in the century. In its early history, the violin had a dull and rather quiet tone resulting from the fact that the strings were thick and were attached to the body of the instrument very loosely. During the eighteenth and nineteenth century exciting technical changes were inspired by such composer-violinists as Vivaldi and Tartini. Their instrumental compositions demanded a fuller, clearer, and more brilliant tone that was produced by using thinner strings and a far higher string tension. Small changes had to be made to the violin's internal structure and to the fingerboard so that they could withstand the extra strain. Accordingly, a higher standard of performance was achieved, in terms of both facility and interpretation. Left-hand technique was considerably elaborated, and new fingering patterns on the fingerboard were developed for very high notes.

Công thức tính số tổ hợp chập của phần tử là:

Question 26: According to the passage, early violins were different from modern violins in that early violins____________. 

Of all modern instruments, the violin is apparently one of the simplest. It consist in essence of a hollow, varnished wooden sound box, or resonator, and a long neck covered with a fingerboard, along which four strings are stretched at high tension. The beauty of design, shape, and decoration is no accident, the proportions of the instrument are determined entirely by acoustical considerations. Its simplicity of appearance is deceptive. About 70 parts are involved in the construction of a violin. Its tone and its outstanding range of expressiveness make it an ideal solo instrument. No less important, however, is its role as an orchestral and chamber instrument. In combination with the larger and deeper-sounding members of the same family, the violins form the nucleus of the modem symphony orchestra. The violin has been in existence since about 1550. Its importance as an instrument in its own right dates from the early 1600’s, when it first became standard in Italian opera orchestras. Its stature as an orchestral instrument was raised further when in 1626 Louis XIII of France established at his court the orchestra known as Les vinq-quatre violons du Roy (The King's 24 Violins), which was to become widely famous later in the century. In its early history, the violin had a dull and rather quiet tone resulting from the fact that the strings were thick and were attached to the body of the instrument very loosely. During the eighteenth and nineteenth century exciting technical changes were inspired by such composer-violinists as Vivaldi and Tartini. Their instrumental compositions demanded a fuller, clearer, and more brilliant tone that was produced by using thinner strings and a far higher string tension. Small changes had to be made to the violin's internal structure and to the fingerboard so that they could withstand the extra strain. Accordingly, a higher standard of performance was achieved, in terms of both facility and interpretation. Left-hand technique was considerably elaborated, and new fingering patterns on the fingerboard were developed for very high notes.

Hệ số của số hạng chứa trong khai triển (với ) bằng:  

Trong khai triển , hệ số của số hạng chứa là:

Question 25: According to the passage, which of the following contributes to a dull sound being produced by a violin?             

Of all modern instruments, the violin is apparently one of the simplest. It consist in essence of a hollow, varnished wooden sound box, or resonator, and a long neck covered with a fingerboard, along which four strings are stretched at high tension. The beauty of design, shape, and decoration is no accident, the proportions of the instrument are determined entirely by acoustical considerations. Its simplicity of appearance is deceptive. About 70 parts are involved in the construction of a violin. Its tone and its outstanding range of expressiveness make it an ideal solo instrument. No less important, however, is its role as an orchestral and chamber instrument. In combination with the larger and deeper-sounding members of the same family, the violins form the nucleus of the modem symphony orchestra. The violin has been in existence since about 1550. Its importance as an instrument in its own right dates from the early 1600’s, when it first became standard in Italian opera orchestras. Its stature as an orchestral instrument was raised further when in 1626 Louis XIII of France established at his court the orchestra known as Les vinq-quatre violons du Roy (The King's 24 Violins), which was to become widely famous later in the century. In its early history, the violin had a dull and rather quiet tone resulting from the fact that the strings were thick and were attached to the body of the instrument very loosely. During the eighteenth and nineteenth century exciting technical changes were inspired by such composer-violinists as Vivaldi and Tartini. Their instrumental compositions demanded a fuller, clearer, and more brilliant tone that was produced by using thinner strings and a far higher string tension. Small changes had to be made to the violin's internal structure and to the fingerboard so that they could withstand the extra strain. Accordingly, a higher standard of performance was achieved, in terms of both facility and interpretation. Left-hand technique was considerably elaborated, and new fingering patterns on the fingerboard were developed for very high notes.

Tìm hệ số của trong khai triển .