A. Đỉnh tròn, sườn dốc

B. Vùng đồi với đỉnh tròn, sườn thoải.

C. Có nhiều đỉnh nhọn, sườn dốc.

D. Vùng núi với đỉnh tròn, sườn dốc.

Lê Lợi nhận được gươm ở Thanh Hóa nhưng lại trả gươm ở Hồ Gươm - Thăng Long. Nếu Lê Lợi trả gươm ở Thanh Hóa thì ý nghĩa của truyền thuyết sẽ khác đi như thế nào?

Lần lượt chiếu và catot của một tế bào quang điện hai bức xạ đơn sắc có bước sóng λ 1 = 0 , 6   µ m và λ 2 = 0 , 5   µ m thì hiệu điện thế hãm để dòng quang điện triệt tiêu khác nhau 3 lần. Giới hạn quang điện của kim loại làm catot là

A. 0,667 µm

B. 0,689 µm

C. 0,748 µm

D. 0,723 µm

Choose the letter A, B, C or D the word that has the underlined part different from others.

A. chore

B. chemical

C. change

D. match

Chất nào sau đây có mạch cacbon phân nhánh ?

A. amilozơ

B. amilopectin

C. saccarozơ 

D. xenlulozơ

Một mặt phẳng nằm ngang được kéo bởi lực F=10N theo phương hợp với phương ngang một góc  30 0 . Thùng chuyển động thẳng đều. Xác định hệ số ma sát biết vật có khối lượng 5 kg

A. 0,1

B. 0,2

C. 0,01

D. 0,02

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 34.

Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.

Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection.

Noise causes effects that the hearer cannot control and to which the body never becomes accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased.

Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each other

Question:According to the passage, what is noise?

A. A byproduct of technology.

B. Physical and psychological harm.

C. Congestion.

D. Unwanted sound.

Mark the letter A, B, c orD on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.

It is a really difficult matter to decide how to solve now. I will need time to think it over

A. to sleep on it

B. to makc it better

C. to make up for it

D. to think out of time