*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.

  Bacteria are the smallest known living things with a cellular structure. These colorless, one-celled micro-organisms exist (31)________organic matter is found: in soil, in water and in the air. Since most of them have no chlorophyll, they cannot use light energy to synthesize their food, (32)_________green plants do.They must get their food in other ways. In this, bacteria resemble animals. However, since they are enclosed in a cell wall, they can only (33)_________dissolved food like plants do. Although most bacteria do not contain chlorophyll, some of them can make their own organic food from simple inorganic (34)________. They do not, however, use light energy for this purpose. Others get ready-made food from dead plants and animals. Still others are parasites. Parasites are (35)________to enter other living organisms and take food from them. In doing so, they often cause diseases or the death of their hosts.

(http://www. englishdaily626.com)

Điền vào số 34

A. materials

B. foodstuffs 

C. supplies

D. resources

3S=1.2.3+2.3.3+3.4.3+4.5.3+...+99.100.3

3S=1.2.3+2.3.(4-1)+3.4.(5-2)+4.5.(6-3)+...+99.100.(101-98)

3S=1.2.3+2.3.4-1.2.3+3.4.5-2.3.4+4.5.6-3.4.5+...+99.100.101-98.99.100

3S=98.99.100

S=\(\dfrac{98.99.100}{3}\)

S=98.33.100

S=323400