Giải các phương trình:  3 cos x   +   4 sin x   =   5

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 31 to 35.

The elementary means of communicating with other people is (31) ____ messages by voice. This fact is widely acknowledged and we recognize the voice as a feature characterizing the identity of a person. The array of voices is immeasurable as no two are exactly similar. They can be nasal, resonant or shrill produced in accordance with the individual physical (32) _____ of the throat                   

One possible implementation of the art of voice recognition is voice profiling used by police analysts as a method of (33) ____ court evidence in trials. Every year thousands of audiotapes with recorded interviews or casual utterances are put to the purpose to help identity the probable culprit. Specialists dealing with the voice investigation claim that people can give themselves away by their accents, infections or other voice attributes like pitch, intensity and loudness. A recorded sample is usually (34) _____ into electric impulses and later transformed into a pictorial recording which is processed by a computer program. Very frequently voice analysts have a stab at deciphering the relevant information which may be mingled with background noise or other interfering sounds until they attain the desired results.

Thankfully, these efforts help the police detect individuals who threaten their victim by phone or inform about bomb planting or those who make offensive calls (35) _____ the peace of decent citizens.

Điền ô số 34

A. reformed

B. exchanged

C. adjusted

D. converted