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loan1979
2 năm trước
Why does a telescope need to have a high-gathering ability?




A.To view stars which do not give off very much light
B.To view stars with a high variability
C.To support a lens of large diameter
D.All of the above
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Các câu hỏi liên quan

Read the text below and decide which answer (A, B, C or D) best fits each space.
The quality of life these days is something most of us take for (41) ……… It takes some radically(hoàn toàn) different experience to (42) ………….this fact home to people. In my (43) ……….., it was spending three weeks aboard a yacht with twelve other people, competing in a major sailing race. (44) …………… I was officially a guest, it was (45) …………..clear to me from the start that there was to be no room for passengers, and that I’d have to (46) ……….my weight.
For the first few nights, none of us was able to sleep for more than a couple of hours at a (47) …………before being rudely awoken by an aggressive command. Then we’d do physically exhausting work in total darkness. Every few minutes we’d be completely soaked to the (48) ……... by a large wave we couldn’t see coming. I shared sleeping (49) ………….. with six other women, with barely enough room to stretch my legs. Soon I found myself (50) …………..for my comfortable sheets back home, a hot chocolate and a warm bath.




A.done
B.taken
C.made
D.announced

Read the following passage and mark the letter (A, B, C or D) on your answer sheet to indicate the correct answer to each for the questions.
During the Middle Ages, societies were based on military relationships, as landowners formed their own foot armies into which they drafted their tenants and hired hands. The infantry that fought its way forward against the opposition engaged in heavy ground battles that proved costly in the ratio of losses to wins. These soldiers carried darts, javelins, and slings to be used before closing ranks with the enemy, although their swords and halberds delivered crushing blows on contact. Such armed forces were active for limited periods of time and had a predominantly defensive function, displayed in hand-to-hand combat.
Because this sporadic and untrained organization was ineffective, the ruling classes began to hire mercenaries who were generously compensated for their tasks and subject to contractual terms of agreement. The greatest idiosyncrasy of a hired military force was that the troops sometimes deserted their employers if they could bank on a higher remuneration from the opposition. The Swiss pikemen became the best-known mercenaries of the late Middle Ages. In the 1300s, they practically invented a crude body armor of leather and quilted layered head gear with nose and skull plates, ornamented with crests. Their tower shields proved indispensable against a shower of arrows, and their helmets progressed from cone cups to visors hinged at the temples. As their notoriety increased, so did their wages, and eventually they were rounded into military companies that later grew into the basic units in almost all armies. During the same period, the first full-size army of professional soldiers emerged in the Ottoman Empire. What set these troops apart from other contemporary armies was that these soldiers remained on duty in peacetime.
Companies of mercenaries were employed on a permanent basis in 1445, when King Charles VII created a regular military organization, complete with a designated hierarchy.. Gunpowder accelerated the emergence of military tactics and strategy that ultimately affected the conceptualization of war on a broad scale. Cannons further widened the gap between the attacking and the defending lineups, and undermined the exclusivity of contact battles.
On a permanent basis, companies of mercenaries were taken on in.............




A.1300
B.1440
C.1445
D.1335

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