Здесь предложение вырвано из контекста и поэтому у вас, естественно, возник такой вопрос. Надо знать контекст, чтобы объяснить этот конкретный случай. В данном примере это время просто продиктовано условием упражнения по отработке формы Future Perfect:
Упражнение 2. ответьте, используя Future Perfect Tense и слова в скобках.
Example: Will Jill be busy at 6pm? (finish essay)
Oh, no, Jilly will have finished her essay by that time.
Will the couple be at their hotel on Monday? (move to the old beach house) [Будет пара в гостинице в понедельник?
O, нет! Они переедут в старый домик на пляже.] Именно из вопроса мы видим, что время действия в ответе должно быть закончено к понедельнику (в будущем) Вот вам и указание на время.
Поэтому указание на время именно в вашем предложении и отсутствует. Но если вы добавите вопрос, который в вашем случае почему-то проигнорирован, то и увидите, что требуется в ответе именно Future Perfect.
I. What is the simplest way of computation?
Answer: The simplest way of computationa is a digital computer in the
strictest sense of the word
2. Is finger counting practised in our times?
Answer: Yes,it is in active use in any school-room.
3. Where does the decimal base of numeration come from?
Answer: Nature unwittingly established the decimal base, with its
10 digit values as a natural mode in which the human race
might express its numerical ideals.
4. What did the limestone pebbles represent in counting?
Answer: to represent numbers
5. What is the etymology of the term calculation?
Answer: The word calculation itself comes from the earliest form
of abacus which consisted of lines drawn on the ground,
with small limestone pebbles to represent numbers.
6. What is the origin of the word abacus?
Answer: The abacus (from abax, an ancient Greek word for slab).
7. What lies in the basis of two-five system of numeration?
Answer: Devising symbols to express specific quantities. The first two were, quite naturally, a two and a five; two because man had two hands, five because he had five fingers.
8. Who invented numbers and introduced them to Europe?
Answer: they originated in India and were introduced to Europe by the Arabs.
II. Discussion questions:
1. Why do the people use the abacus in the time of scientific and technological progress? - people use it as a physical aid to keep track of the sums, the carrys, etc
2. Did nature provide man only with a decimal base of numeration?
3. How does the abacus function? - it is a calculation tool used by sliding counters along rods or grooves, used to perform mathematical functions.
4. How did the first mathematical symbols come into existence? - they were signs for the depiction of numbers — ciphers, the appearance of which apparently preceded the introduction of written language.
5. What are the shortcomings of the abacus?
6. What have abacus and computer in common?
7. What do we call the abacus's native sister in Ukrainian?
