Một đề xi mét bằng bao nhiêu xăng-ti-mét ?

A. 1 dm = 1 cm

B. 1 dm = 10 cm

C. 1dm = 100 cm

Viết thành phân số tối giản

30% = ………………………

Read the following passage and mark the latter A, B, C or D on your answer sheet to indicate the word or phrase that best fits each of the numbered blanks . Fill in the appropriate word in question 35

      Why is it that many teenagers have the energy to play computer games until late at night but can’t find the energy to get out of bed (35) ________ for school? According to a new report, today’s generation of children are in danger of getting so (36)_______ sleep that they are putting their mental and physical health at (37)_______. Adults can easily survive on seven to eight hours’ sleep a  night, (38)_______teenagers require nine or ten hours. According to medical experts, one in five youngsters (39)________ anything between two and five hours’ sleep a night less than their parents did at their age.

      This (40) _____ serious questions about whether lack of sleep is affecting children’s ability to concentrate at school. The connection between sleep deprivation and lapses in memory, impaired reaction time and poor concentration is well (41) _______. Research has shown that losing as little as half an hour’s sleep a night can have profound effects (42) ______how children perform the next day. A good night’s sleep is also crucial for teenagers because it is while they are asleep (43)______ they release a hormone that is essential for their ‘growth spurt’ (the period during teenage years when the body grows at a rapid rate). It’s true that they can, to some (44) ______, catch up on sleep  at weekends, but that won’t help them when they are dropping off to sleep in class on a Friday afternoon.

            By Tim Falla and Paul A.Davies, Solutions Advanced. OUP

A. behind time

B. about time

C. in time

D. at time

Ma sát của má phanh và vành xe khi xuống dốc

công thức về khối lượng

mBaCl2 + mNa2SO4 = mBaSO4 + mNaCl

20.8 + 14.2 = 23.3 + mNaCl

          35       = 23.3 + mNaCl

       mNaCl   = 35 - 23.3 = 11.7

1.A

2.A

3.C

4.D

5.D

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